What exit taxes exist in the US if you cannot maintain citizenship in both?

Of course, but 80k is also on the high-end for Paris jobs as well and buying an apartment in or around Paris is not cheap at all. And most companies in France, even in tech, except maybe the few high-end international ones like FANGS or Mistral and Datadog, explicitly request French language for their workers, whereas English is enough for most US jobs.

I'm EU citizen and looked towards working in France even for the lower wages, but the French language mandates for most jobs are really off putting, even in European companies like Airbus.

Like I'm willing to learn the language, but I'd need at least 2-3 years to get remotely fluent, and it's just not worth the added effort, just for the opportunity to get the average Europoor wages that I can anyway get with just English and my mother tongue anywhere else in EU without any additional effort.

Even in my small Eastern European home town I hear more and more french speakers in the city center every year, and when I talk to them I understand they're all here to study medicine or get junior tech jobs, which is insane to me and speaks volumes on how bad the French jobs market must be for the youth when Eastern Europe is now an immigration hotspot for the french when 20 years ago it was the opposite.

So no, Paris/France is no European SV equivalent, not by a long shot, even by the low European standards. Amsterdam is probably the closest thing to SV the EU has, after London left, but housing and CoL there is insane and even that has significantly fewer VC funding than SV and even London, which highlight just how poor the EU is by comparison to the US at tech funding.

Like I want to get the EU to the top an catch up to the US, but I don't see how that's possible with such limited tech funding and glass ceilings based on having the right nationality and language requirements. EU will never beat the US, at least not in my lifetime.

Most people would make way less, at big French companies you won't make 80k until late in your career as an IC (they don't have a staff+ track).

So 80k sounds like a decent guess for the top 10-15%.

I don't think that's a good assumption. 80k is rather high for Paris. That's a Google salary at their small office there (or it was when I checked a few years ago). I think the OP's comparison was pretty reasonable.