The Future of the Time Machine

If we were to truly harness the power of time travel into a 'time machine', what would we use it for? would we go forward and prevent the earth from eventually being destroyed? Or would we use it to go and rob both future and past earths of their resources? Or would the 'genius' who invented it use for, simply, thrills and fun? No, the CIA would be busting down his/her door in minutes. Scratch that, seconds. Would this wonderful 'time machine' be widely distributed, or be kept private, and forgotten, until a time of need? I think the latter, because if it was a worldwide 'trend', then everyone would be travelling all over, and  getting stuck, accidentally leaving it in the past, (or future) and causing all kinds of trouble. Who could the government 'trust', to use the time machine appropriately, and not cause trouble and mayhem for all inhabitance of this planet, and, possibly, all others. Say, if someone went back to the time of the Big Bang, their very presence might change if the Earth, or any of the other planets, even the sun, even will exist. That's a happy thought.