It's the same story across industries. Europe missed the fifth generation fighter aircraft boat, so now everyone is buying F-35s. Even if FCAS and Tempest ever get off the ground, the F-35 will be too entrenched in allied air forces to be dislodged.
Rockets too. Europe missed the reusable rocket boat, and now SpaceX is eating the Ariane's lunch, for the most part, except for politically sensitive European projects for which they still use more expensive Ariane launchers. The rocket market is more prone to disruption however, because launches are a one-and-done kind of thing. Switching launch provider is easier than switching operating system or the composition of an air fleet.