Already happy now, in this time, thank you very much.
Time Travel? If it happens one day will that make you happy?
Nope. What's in the past, I'd like to leave it there and never see it again. What's in the future, I can wait for it to happen when it's time. If it ever happened, I wish y'all luck on your journey, but I'll be steering clear of it.
Yes as long as it is controlled and limited to people who know not to mess up time. Historians, Scientists, Theologians, Geographers, and Economists are just a few of the people that could benefit from time travel.
I will probably be a little anxious that someone will mess up the space-time continuum and the world will blow up, or something.
But yeah, I'll also be happy that humans have mastered what war once thought impossible. Admittedly, most people who are alive today probably won't be alive if humans ever time travel, but it's a cool thought.