Well if nobody form the future has shown up yet, it suggests that we not only have not mastered it now but we probably never will master time travel. So we may just as well surrender on that and worry about more realistic dreams like building new colonies on Mars.
If time travel were ever possible I suspect it would be a one way trip forward.
If people in the future are smart they would prevent a traveler from returning to the past anyway.
I just want my flying car.