You're goddamn right I would sell out. You always hear the story of that guy who sold a 25% stake in MSFT in 1982 for $600 or whatever it was, which is a legit enough argument, at certain numbers of scale.
In *this* case, $3 billion (even halved to 1.5) is waaaaaaaaaaaay up the scale of current value vs maximum theoretical value. $3 billion now for something that if everything went 100% perfect might later go for what, $10 billion? $20b?
Not really the same as $600 in 1982 vs $50b in 2000 or whatever. $3b is easily enough to be rich as shit the rest of your life even if you don't have any other ventures (which you easily could to get even more success with that much bankroll).
I'd take it in a heartbeat and probably throw in a free BJ for good measure