The problem is if they take the young gifted entrepreneurs with them. I heard anecdotally that they were already leaving e.g. for London and that was before this latest tax increase.
Bernard Arnault should be hailed as an example, not a traitor, for leaving France and getting a Belgian citizenship.
Postulating a Unified Europe by pushing the ongoing de-nationalization of the EU member countries is absolutely antithetic to the expectation that tax payers should feel obliged to pay taxes to their home country, and not switch to the one most beneficiary for them.
Which is precisely why de-nationalizing Europe is such a bad idea.