The only reason not to sell is because you believe Google can't break your business before you get a better offer or you can IPO. If you think they can do that then you don't really have much of a choice.

Founders tend to factor this in to their thinking from the start. "Acquired by Google" is often considered a desirable exit goal.

IPO is kind of a sale too. (Though it's relatively easy for founders to keep control in an IPO, given the market's acceptance of weird share voting arrangements.)

If the other option is being broken then of course you sell. Even if you could make more money in the long run if they weren't holding a gun to your head.