I got from the other comments that he got the 2B by owning part of the now very valuable company, not by working for a salary. Assuming he picked a good enough successor that didn’t completely ruin Dropbox, he should still have pretty much the same net worth without any work, no?

Your presumption is that it's about the money for everyone.

But there's a lot more at play when you are rich enough to not worry about money.