With all due respect to Stephen Hawking and Niel deGrasse Tyson, the reason humans fight other humans for resources is that we all live in the same resource-constrained environment, and we have developed various cultural and religious imperatives which prefer hegemony, exploitation and colonization over cooperation.

But resources are abundant in space, and there's nothing that can be found on Earth (barring life, specifically) that can't be found in orders of magnitude greater quantities elsewhere. It's like our entire solar system is a buffet but we're the only dish with flies buzzing it. If you're looking for a meal, you wouldn't even bother with that.