They want to dominate the world. That is why they invaded Iraq. That is why they bombed Libya to smithereens. That is why they funded, armed and trained a dirty war in Syria that cost hundreds of thousands of lives.

And that is why they move into Ukraine, even though Russia made it very clear that this was the brightest of red lines. They are also megalomaniacs, which is why they'd rather provoke Russia and try to instigate regime change there rather than to abandon their attempted conquest of Ukraine.