You could argue saving at least one universe from a terrible fate is worth it - but it's not. That universe is destined to suffer some terrible thing, and interfering won't change that. Nature will take it's course, one way or another, and preventing one event will only cause another in that universe. It will also not affect our universe because, you know, multiverse theory, but we also probably won't be able to get back to our own timeline.
Think about it - if Multiverse Theory is true, then we are not only travelling back in time, but also to an alternate universe - similar to ours, but with differences. If we go forward in time, we are only traveling forward in THAT timeline. The reason why going back in time would send us into an alternate universe is because (theoretically anyway) we are the main timeline, and any decision we make creates an alternate universe/timeline where a different decision was made. We can't do something before we do it, so going forward in time will just bring us forward in time of whatever timeline we are in. Going back in time will probably send us back in our own timeline, but as soon as we stop travelling, we have an effect on that universe which is what causes us to be in an alternate timeline to our own.
TL;DR or just didn't get any of that - Going back in time is effectively dimension hopping - going into other dimensions.
Are you kidding? The country has spent so much money and spent so much time preparing for the big event. It would be an outrage if the Olympics were canceled at the last minute. Think about those athletes who put in years of hard work to get to the Olympics. We would be insulting them if we canceled the big event, which is now about four weeks away.