So I asked him. "First of all" he said "When a guy has the possibility to go back in time, he would not go to work and raise a familily - he'd go back over and over again to bang Rachel McAdams' brains out. I'd be more like 'Groundhog Day'".
For your information, "Groundhog Day" is a movie from 1993, where Bill Murray is forced to relive the same day over and over again. Which isn't too bad a deal, according to my boyfriend, unless you want to get any work done. Because you can't take anything back except your own memories. Even your body is reinstated - since death also doesn't apply. It's a perfect way to attain immortality.
But that wasn't his only criticism. What happened to his former self when he jumped back? He didn't have to move in the cupboard first so he can exit later on. That was the plot of the movie "Primer" from 2004. You'd activate the device, your former self would crawl out a short while later, and you'd enter the box in a few hours. No paradoxes there. The box was there when you got out and you would in fact end your existence when you got in.