Not making a partisan argument, as I don't affiliate with either party, just stating that both sides exhibit support for DoD/IC activities and both were likely to support equal, if not increased, levels of spending on them
https://www.google.com/search?q=clinton+presidency+dod+budge...
And then the massive DoD budget increases under Bush, post 9/11 and Afghanistan/Iraq related which kept a lot of large and medium sized defense contractors riding the gravy train for a very long time.
As best I can remember Obama did not significantly shrink the DoD budget as a whole, though it did drop a bit from the 2006-2007 peak under Bush, though some programs were cancelled.
It could be that, like many right-wingers or libertarians, he saw in Trump an opportunity to break with the status quo and had the vague impression he'd get the things he wanted, or could manipulate Trump in the right direction.
But has Thiel personally profited in any way from this? He's reviled in Silicon Valley, and the Trump association hasn't obviously brought him anything new.
Have Thiel's ideological priorities been satisfied? He's known for being a hard libertarian, and he supported a man who was openly nativist and who has implemented tariffs. Failure on that score.
Thiel seems like a fairly callous person when it comes to race (as a student, he backed apartheid[1]). Trump may be more aligned with him there.
[1] https://medium.com/indian-thoughts/my-conversation-with-pete...
A Biker/Gang Member may not be attractive to most people, but to the portion of the population that prefer someone like that, they have much fewer anti-social males to choose from, and those individuals can do well at the bar.
Given Trump's blatant admiration for authoritarians and authoritarianism, I'm skeptical that Thiel's support had anything to do with libertarianism.
Indeed, given Thiel's founding and constant promotion of Palantir (which feeds at the trough of the military-industrial complex and government contracts), I'm skeptical that he makes many life decisions based on libertarian principles.
Had Trump lost, Thiel would have probably diminished his standing with the Clinton administration significantly. But, due to the crowded field, it would have been a small standing to begin with.
And here's the crux: Thiel has held controversial opinions for a while. He probably figured his association with Trump wouldn't really move the dial on his likability much, and he seems to enjoy being contrarian anyway.
So, anyway, there's my theory. Risk asymmetry. A lot to gain in the event of a Trump win, little to lose in the event of a Trump loss.