(Spoilers All) What was Vargo Hoat's Endgame?

I'm doing a reread of the books, and can't quite seem to figure out Vargo Hoat's endgame.

I understand why he took to working for Tywin. They seemed like a good match for one another. I also understand why he betrayed Tywin and gave the castle over to Roose Bolton. At this point, he decided he wanted to side with the Northerners.

But why in the world did he cut of Jaime's hand? He wanted to drive a wedge between Roose and Tywin, but with himself in the middle? What was his plan?

He couldn't eventually go back to Roose. Roose was upset that Vargo tried to screw him over. He couldn't go back to Tywin, he cut off his son's fucking hand. But whatever, if he decided to cut out and go rogue that would sort of make sense. Make a bunch of money with Tywin and then book it across the Narrow Sea. But he didn't do this...he waited for the Mountain to show up and wreak shop.

Am I missing something?