I think it's a depressing question, although commonly asked of folks that are perceived as 'older' . Most people have some regrets - but why focus on that which is rued but can't be changed? What's the point of dwelling on this? Especially now - are you planning to enter your senior years cloaked in regrets?

If you want to ask an older person a philosophical question, I 'd suggest
asking what they're proud of, what are the sources of their happiness today,
or what challenge did they meet and rise above, especially ones they never thought
they could do when they were young.