I don't really get why a company wants to be acquired if they're already best in their class and therefore will be raking in money for the foreseeable future. Don't they get a big payout either way?
I feel you there. Sticking around long-term may also not be sustainable for everyone.
It takes a lot of energy (to wade through the ups-and-downs) as even running a co in a "profitable" situation isn't always as rosy as one hopes it to be. There are lawsuits, internal politics, competitive drama, etc.
Cashing out allows one to regain some headspace, take care of family or address other personal matters that need attention (or have been inducing some strain) and finance the next idea that one may have had on their minds.
Furthermore, things tend to get more corporate-ish as orgs grow because more structure is needed/required and this may not fit every personality type very well, so I guess builders will do themselves a service to hop out once the train shifts into a different gear to allow folks that are better at that game to take it from there.
Just hope that Adobe doesn't end up ruining things because I feel that is usually the issue with acquisitions. The buyer just dulls things down or they actively kill to push one of their overlapping overrings.
They now have cachet/reputation, and deeper pockets, and can easily start up and get funding for anything they might want to do.
Just making a slow, healthy profit with a company might not be enough for them.