You’re forgetting that your present is their past. They’re not going to change things in the past that led to such an advanced society that time travel becomes possible. They’re no more attached to your perceived suffering than you are to Genghis Khan’s victims, or Shaka Zulu’s, or Henry the VIII’s wives. It’s just academic to them. IDK if you ever watch star Trek, but it took WWIII, and the Eugenics Wars to lead to the post scarcity, intergalactic Federation of Star Trek. It is arrogant to think there’s something special about our era that would lead a time traveler here to make corrections. This is of course discounting the newer concepts about time travel, that they wouldn’t be changing anything about their present anyways, they’d just be creating another timeline.