While I totally agree with this comment, especially from experience knowing that the reality of an acquisition is far from the rosy picture promised to everyone, the truth is that founders and especially investors are motivated by the exit.

Some founders start their companies to be flipped. Some start with the intention of going for the long-game but find the reality of competing in the market exhausting and emotionally draining. Some realize that they won't be able to capture the market share they want. Other times internal strife or conflicts with investors get in the way.

There are many motivations for acquisition and the realities of the difficulties of startups make any good offer very appealing. It's very hard to resist.