It's a much deeper relationship than that.He's an idiot, he could just buy some roadrunner steaks from Acme Co. The money he's wasted on rockets and rollerskates over the years is scandalous.
Mr W.E Coyote is clearly getting food elsewhere.
As you say he has access to a small fortune.
It would seem that he thrives on the primal desire to hunt.
If that were to be taken from him, ie catch that annoying f***nut, Wylie would be left with nothing.
He'd be a shell of his former self the shrewd, cunning, machiavellian Wylie would cease to exist.