You do realize that he didn't even want to let go of XFL in the first place after week 2 when it tanked, right? He didn't want to throw in the towel in 2001, despite the enormous amount of money he lost and was going to lose, and eventually only backed down because no one would give him a TV deal.
Vince is (or rather was a genius) in certain things about wrestling, but outside of that he has a very narrow view, can often be out of touch, and can be single-mindedly obdurate once he resolves to do something. He's a smart guy, no doubt, but he has his flaws and blinders, and increasingly so in the past 15 years. Every venture, without any exception that I can think of, outside of wrestling has failed for him. He also his this desire (always had) of being *more* than just the 'wrasslin' promoter' which probably stems from his well-known latent self-loathing about the wrestling business, so he isn't just content to be successful/good at wrestling. He has to be more than that. And part of him, because he is super competitive, wants to avail the XFL failure, and all the ridicule that was poured onto him in the aftermath of that. He went from being perceived as the Walt Disney of wrestling in 2001 to being an utter low-rent laughingstock because of the XFL.
I'm not sure if he's bringing the XFL back, but I do think he wants to make some sort of - probably ill-advised - move into the NFL, in 2018 of all years.