I would blame primarily the higher gasoline price. When gas costs two times more than in US, people suddenly start thinking more whether they really need full size truck to take their groceries.
Might be a factor but take a look on the streets of Munich and you'll see a lot of what I call "street-legal tanks"...
They're about status. Plenty of people want something small and cheap, and in London EVs don't pay congestion charge, so the incentive is even higher. But that said, if you're an obnoxious commodities trader who just spent £10m on that new place just off the King's Road, you're probably going to buy your wife an X5 to keep the kids safe...
They just have them as a status symbol because they want to feel important/powerful/rich.