They control Europe's digital infrastructure and are able to increase rent to usurous levels (tarrifs!) because Europe is dependent on their digital services. Without digital sovereignty, Europe has no sovereignty and will quickly become a modern colony from which wealth will be extracted.
The reason the US is able to raise rents (tariffs) has nothing to do with Europe buying US digital services.
The tariffs are on European exports. The problem is Europe has a weak domestic consumer market and is dependent on selling stuff to the US, not buying from them.