That's, frankly, a pretty small price to pay. Entrepreneurial dreams are a dime a dozen, and many (most?) of them don't even have a good social impact. Some individuals whose dreams were "crushed" may feel sad, but unless we're talking about people losing their livelihood and ending up in poverty because of Microsoft, it's not even on the map compared to what Gates is doing now to help the world.
I think it's less of a big deal because I'm in my 40's now and think about the common good in broader terms that encompass poverty and development and not just my parochial interests as a young hacker, yeah.
On the other hand, if Bill Gates doesn't spend money curing diseases in the third world I'm not at all convinced that someone else would come along and fill in that space. After all, they could very easily match him today with all the work there is to do.
You may be right, but this is a pretty toxic belief and seems to be constantly used to justify ethically questionable things.
Conversely, have you thought about all the third world disease deaths the guy's money has prevented?
To be clear: I was in the anti-MS camp from way back when that means "OS/2" instead of Linux. I was no fan, and still don't use their software for anything meaningful. But "dreams destroyed" is a bit much.