Football

Good question.

Money
lure of the premier league
a new challenge (not much more he can do in Germany)
most of his stars are probably going to leave in the next season or two
Owners who match his idea of building up young players, rather than buying in established stars.

I'm not sure he would leave, but if he did, I would love to see him at LFC, above any other manager right now.

John, it is Klopp not bekloppt (to believe what you bope).