I think that there are two reasons that make sense to me. One that he wants to die and that he thinks he can die somehow through the curse. Two that he wants to ruin the Evil Queen. It might be both.
I keep wondering who has the dagger. And the thought that maybe Regina’s mother had the dagger at one point, so maybe Regina’s father has it so maybe Rumpel wanted Regina’s father dead. That seems a little convoluted, but i thought i’d throw it out there.