Meta; US produces well funded startups presumably because the exits are good. Investors don't mind the risk, expecting an outsized return.
Exits are good, perhaps, because US stock valuations are just much better. Investors are happy buying at a higher P/E ratio, expecting it to go up in even further, and make a good return.
Now, for a long time, there has been talk of US equities being woefully overvalued. Of course a value is only what investors are happy to pay. But supposing this is true, and US is due a major correction, Trump's "shock therapy" on markets might actually achieve it. If that's true, US valuations would drop relative to the rest of the world (this hasn't really happened yet, most of developed markets moved roughly in unison - but it's early days perhaps).
If that happens, US might actually stop looking like a most attractive VC market. This would presumably lead to a general drop of VC investments - but also to a greater geographic spread in VC investments. In particular, more money going into things like European space companies, as opposed to US ones.
There's a lot of assumptions here. Maybe US equities have higher valuations because they are genuinely better, or a correction won't actually come. But it always puzzles me why the US seems better at churning out well-founded startups for no totally obvious reason, and maybe that's it.