* Was it illegal? Nope.
* Did it only have selfish goals? Yep
* Did it necessarily doom others to losses by timeliness and first-come-first-served? Yes
* Did he have equity of access with others? Hell no. he's head of the queue.
It's not "wrong" in a narrow sense but most people are on point #2, they dislike Thiel (as I do) and so "judge" him to political philosophy, not to legalism.
He's not markedly more wrong than other people in his situation. He may well be significantly smarter and asymmetry in the economics space, is held to be counter-productive overall. Of course, you're naieve or a fool or both if you don't exploit it.
Maybe you have a different interpretation of "wrong" ? And, I can't fault his logic: This is basic 'win' thinking. Why hang around? What's in it for him, long or short term to wait?