Isn't the problem that European tech companies are sold to American companies? There are and have been countless of European chipmakers but they are usually bought by Americans.

European companies grow to a certain size, and are then either sold to an established American company or relaunched from Silicon Valley with American investments.

I think most of this is tax driven. American tax rules allow venture funds and also private wealth to accumulate and grow easier than European counterparts. The American government simply allows its business and private individuals to accumulate money via off shore companies in the Caribbean. The US deliberately allows this.