To be honest, I stopped watching wrestling a long time ago, when I was a kid I thought it was for real, there's no internet that time so I am no educated with this things, when I learned it's just a fake show then I stop watching it, instead I focus on real physical sports like boxing and UFC.
I too used to love the show when I was a kid, like most of us as we grow up we realize that it all fakes start losing interest. but it was still a great experience watching it
Why would Tyson Fury fight for WWE, last boxer I knew who fought in WWE was Floyd Mayweather fighting the big show.
Money(or maybe for the experience), that's the only reason why would someone like him, a famous boxer, would fight in WWE.