I guess because it sounds like you lose all of that by confining them. They're not really legends or legendary if they've been captured. And it's not all that great being powerful. It comes with a lot of responsibility, actually. You think you can do all sorts of things, but it's not actually like that. [Jade telling it how it is.]

Besides, there will be people who'll want to be friends with you because you're powerful, but they don't actually care about you. Just the power you possess. You'll make a lot of enemies and it doesn't sound all that fun.

Killing people doesn't sound all that great either. If you kill people, than who will want to willingly be your friend?

It sounds pretty shitty.