Selfishness is part of the human condition. Tribes needed to fight over resources and mark their territory in order to keep the tribe alive. It’s in your instinct.
There have always been borders and territories, and there have always been fights and wars over it.
I don’t really see how your “if you don’t use it” policy applies here, and I also think the problem of this topic is easier than that.
Well if we find one we have proof of advanced life elsewhere in the universe. That’s the most important thing. Reaching out will take millions of years.