I don't think he's investing in the hopes that Trump will pull of a long shot. I think he has a different goal in mind. He said in his speech at the RNC that the country is broken and that Trump is the only one who can fix it. I have no doubt that he believes the first part - he's said as much for a long time - but I do doubt that he really thinks Trump is the man to fix anything. Thiel may be nutty according to some, but he's not an idiot and the only thing Trump has ever been good at is self-promotion and entertainment.

I think he thinks the country is broken and _someone_ has to fix it. He's supporting Trump and investing in his campaign even at this late, seemingly forgone stage, in order to build credibility with Trump's base and conservatives in general. If he wasn't an immigrant I would think he might be aiming for the presidency himself, but he probably just wants to be an influencer or power broker.