The point is that it's 8500 hours of free time used for exercise. It's time when you're not eating sleeping or working.

So it's not exactly the same. For people who have very little free time due to commute, work, children, etc. It's harder to spend half an hour of free time a day on exerciaing.

I mean I do agree with the premise that exercising is a good return (especially since the better sleep quality should be factored in) but I think the person you're replying to has a point when he says that saying it's one year of life is not really comparable