People who build companies like that tend to be Type-A personalities. They're driven, always needing something to do. I can't imagine having that much money and wanting more. I mean, I understand needing to keep busy, but find a cause - a charity or something - and put the energy into that.
I loved my job - the actual work itself - but the office politics became too aggrivating, so when I had the opportunity to retire at 55, I jumped on it. This was only possible because of a pretty frugal lifestyle (thanks in part to my low-maintenance wife), a couple of lucky breaks, a lot of work, and a few good decisions.
Technically I'm semi-retired, since I still do some freelance work part-time. That gives me a routine, keeps my brain cells active, and supplements the retirement income. It's been two years and I have no regrets at all. Like you, I feel blessed to have what I have. It would be easy to sit back and say, "Hey, I earned it," and to a large extent, I did, but I had opportunities that not everyone gets, so in that respect, I'm very fortunate.