It gives you both, but at what cost? If you have a spouse or child, that’s probably not going to happen again in round two. You’re going to make different decisions that take you on a different life path. Even if you made the same decisions, is your significant other actually going to fall in love with you when you’re going on the first date with 10 years of history already? You’re not going to bring that new relationship energy with you and you’re going to seem weird since you already know them so well. Even if you win them over, you won’t have the same kid. The odds of the same sperm finding the same egg are millions to one, possibly even higher since you probably won’t do it on that exact day. What about all your lifelong friends? Are you actually going to form meaningful relationships at 6 or 10 years old when you have the mind of a 30 year old, or whatever you are by that time? Probably not. I think the cost to go back would be very high.