It's impossible for humans nowadays, but it is practically possible; one only needs enough delta v, which requires energy. There's certainly enough energy in existence to throw the Earth into the sun.

Yes, obviously this is absurd. But I'm just extrapolating your argument to make an argument: It is silly to expect any economic theory to account for throwing the Earth into the sun. But its also silly to expect an economic theory to account for other absurd behavior, like throwing gold into a volcano.

Every economic theory relies on simplified models of human behavior. Humans behaving irrational is not usually part of those models; the ways humans can behave irrationally is infinite - not useful for a model.