I read a lot about traveling back in time to kill Hitler. Wouldn't that make Israel cease to exist? Even the person going back in time would cease to exist most likely. WW2 doesn't happen and my grand parents on both sides never meet.
I'd go back in time to save my father. Spend more time with friends and family while I had the chance. Invest in the right areas as well.
The "kill Hitler" time travel idea is a classic example of how trying to do an objectively "good" thing can result in unintended consequences. It usually is based on the idea that if Hitler was killed before he rose to power, then WW2 and the Holocaust would be avoided and hundreds of millions of lives may have been saved. However, it takes a very myopic view of the world at the time
1) Imperial Japan and Stalin's USSR still exist even without Hitler - there still would have been major geopolitical issues and probably a war still
2) It rides on the idea that Hitler basically the genesis of all the Holocaust stuff and the mastermind of WW2. While he did clearly push for those, he didn't invent the ideas for either. It is just as likely another person could have risen to power that would have subscribed to the same viewpoints
3) As an extension to #3, a more competent person than Hitler in power could have resulted in a very different outcome in WW2. Hitler made a lot of decisions that really hurt Germany in the long run, especially all the Eastern Front stuff
4) Even if you somehow got the outcome no WW2 at all, the global stage would be completely different. There would be significantly reduced technological advancement, which would have cascading effects. Jet, Rocket, Computers, Atomic, etc. The changes to the timeline on Earth would be massive. Those technologies would no doubt be eventually refined and developed, but the levels they reached by the end of WW2 may have been delayed for decades.