By "market leaders" you mean the very many American companies fuelled by unlimited investor money that lose billions of dollars a year with no chance of ever turning a profit?

Even if that’s the case, why aren’t investors willing to invest in EU tech companies at the same level?

On top of that the US is a rather homogenous market with a single language vs. 27 conuntries with 27 different languages (in reality more) and quite a difference in local laws (even if all are compliant with EU-wide laws). IIRC there's also an expectation in Europe that companies should actually turn a profit at one point (though with influc of American money this is starting to change, too).

You still get ASML and Infineon, SAP, Adyen, Amadeus etc.

Outside of Software, aeroplanes and luxury goods come to mind.