"Flip" means to get rid of it. To the contrary, founders may well be in a hurry to scale UP, which you certainly can do when acquired by the right company, like Google (as you know).
Flip implies a very quick sell to turn a fast profit. Building to flip and building something up that you personally acknowledge to be valuable to other companies is very different.
Yes, startup founders may acknowledge to themselves that an acquisition is their goal for an exit. But that acknowledgment is at the start. In the groundwork. You don't focus on trying to sell throughout -- you just try on making something people will want to use.
And "maybe we'll sell"? Who are "they" kidding?