A recent survey reports that the rich expect to live to 100 and are planning accordingly for a lengthy retirement.

How long we’ll live is one of the biggest mysteries in life. No one can know for sure.

However, a group of wealthy people are pretty certain they’ll live to be 100 and are making financial plans for a 30-year to 40-year retirement.

According to the UBS Investor Watch, which tracks insights of more than 5,000 people with at least $1 million in assets, 9 out of 10 people surveyed stated that they are making changes to their spending and long-term investments in order to finance their anticipated longevity.

But should they make those plans just because they are rich?

“Average life expectancy has been going up at the population level, but there is mounting evidence that the increases have been larger for high socioeconomic status groups,” Susann Rohwedder, PhD, senior economist and associate director at RAND Center for the Study of Aging, told Healthline.

She adds that the wealthy have, statistically speaking, a greater chance to make it to 100, so planning for this possibility is reasonable.

At the same time, there is uncertainty associated with each person’s length of life, and that averages, even if calculated for separate groups such as the wealthy, mask large variations across people.

Life expectancy in all industrialized nations has increased over the years.

However, Dr. David Himmelstein, co-founder of the Physicians for a National Health Program and a lecturer in medicine at Harvard Medical School, says that at the broad population level, it is clear that having money will help you live longer.

He does note that it is still unusual for even wealthy people to live to be 100.

“We do know that the difference between the wealthiest and poorest Americans is about 10 years for women and 15 for men, so there is a big spread with wealthier people living much longer than poor people,” Himmelstein told Healthline.

The underlying causes for the survival differences are complex and reflect the interplay of health and economic status, as well as other factors over people’s lifetimes, Rohwedder explains.

“It may be tempting to think ‘If only I was wealthy, my survival would be so much higher too.’ But if I dump tons of wealth on you, would that insure you live as long as other wealthy people? The answer is probably no,” said Rohwedder.

For instance, differences in average survival have been found comparing high versus low education, or high versus low income groups, leading to the idea that good health helps people to do better at getting a good education and perform better at their jobs.

That also leads to higher income and wealth.

In turn, with higher income and wealth, people can afford a healthier lifestyle.

Rohwedder emphasizes that these patterns reflect correlations and should not be interpreted in a causal manner.

Himmelstein agrees, noting that more education influences lifestyle outcomes.

“Health literacy and nutrition literacy are partly determined by education level and what your job is like and housing is like. If you have more education, you are more likely to have access to the better pieces of housing and jobs,” he said.

Healthy behaviors, such as exercising and eating a balanced diet, also help increase the chances of living longer, while not smoking is the one lifestyle choice that research proves increases your chances of living longer.

However, the Centers for Disease Control and Prevention (CDC) reports that in the United States, people living below the poverty level and people having lower levels of educational attainment have higher rates of cigarette smoking than the general population.

While having access to medical care or the money to pay for medical treatments seems like it would increase longevity, research isn’t concrete.

Himmelstein says medical care is probably the second most important determinant of how long a person will live next to everyday lifestyle circumstances, such as housing conditions, diet, exercise, job, and stress.

Still, research shows that people who are underinsured (pay high co-pays and deductibles) or who don’t have insurance feel discouraged from getting the care they need. Those financial barriers to access of care have a small effect on mortality.

“We have studies of uninsured people over the course of years [that show] for every 800 people who are uninsured, one will die each year because they are uninsured,” Himmelstein said. “We don’t know the exact causes of that and if that adjusts for things like how wealthy they are, whether they smoke, their race, education, and so on.”

He also points out results from surveying people who experienced heart attacks but delayed going to the emergency room because of financial reasons.

“That delay can be fatal. We also know that if you give people who have had a heart attack, free medications for what’s needed after their heart attack, they are less likely to have another heart attack or similar event in the months following than those who have co-payments and deductibles for their medications,” Himmelstein noted.

Research also shows that children with asthma whose families have high co-payments for medications are more likely to end up hospitalized than kids with asthma whose families don’t face high co-payments.

Overall, though, Himmelstein says controlling blood pressure and advising people to stop smoking is probably the most important impact that medical care has on determining life expectancy.

“It’s intervening to help people at the early stages of illness, or before illness has developed, where we can predict the illness may develop, and also treating conditions like high blood pressure,” said Himmelstein.

When it comes to high-cost tests such as colonoscopy, Rohwedder says that it’s not always clear if access will extend life.

“The hope is that treatments help, but we don’t know if sometimes the more treatment you get, the more things can go wrong,” she said. “When questions like, should everyone have the right to so-and-so test at age XYZ arise, we have to think about not only the cost of these tests, but also the issue of what kind of follow-up tests do these tests prompt, and will they potentially cause aggressive treatment that does more harm than good.”

On a broader scale, data from the Organization for Economic Cooperation and Development health database, which collects comparable data from several wealthy nations, found that compared to other wealthy nations, Americans have a shorter life expectancy until they turn 65 years old. Americans who make it to 65 tend to live longer lives.

“It’s quite clear that the U.S. is near the bottom for life expectancy at birth, but does pretty well from 65 on. It’s suggestive… that the universal coverage of Medicare helps improve our standing relative to people in other nations,” said Himmelstein.

And if you make it past 65, whether you’re wealthy or not, living longer means you have more years to finance.

“It’s not just an issue of the super-rich in the U.S. Everyone has to understand that the number of years they will have to finance will most likely be larger than those of their parents,” Rohwedder said. “The hardest part for everyone is planning for the uncertainty around these averages of survival.”