I'm like a bunch of monkeys with typewriters. Give enough monkeys enough typewriters and one of them will write Hamlet.
We target Mars simply because it's within our reach, not because it's more interesting or useful than the other planets. It's simply one we can actually get to. A phenomenal waste of money which could be spent in a multitude of better, more rewarding ways.
It's a relative thing. Much more can be learned for far less money right here on Earth, like cures for diseases, ways to harness energy while polluting less, how to get along with others instead of starting wars. Pretty much anything Mars can teach us can be simulated in a laboratory.