>I wonder how the health damage of sitting at a desk for years compares.
Not comparable, the only real risks of brain damage sustained while working a cushy software job are injuries sustained while commuting and reading really bad HN comments.
Money is no substitute for health.
It will just sound like a "philosophical tidbit" until you get hit by a health issue for which you'd give everything you own to get rid of. Then you'll really understand the meaning of it: no matter how rich you are, you still can't have a decent quality of life.
It's not sitting that is the biggest damage but the amount of life lost doing things you don't care about as much as other things you could be doing with your life.
Comparing apples to oranges. One happened in the past and the other might happen in the future. Plus, there are exercises for problems with sitting, so one can continue to sit for a living and not experience any of those problems.