Sagging isn't going anywhere, no matter how many old people complain about it. It's no different than when old people back in their day would complain about them doing the bop and the mashed potato all over town. These are just the things that the youth does. As much as people love to sag their pants, no one likes seeing underwear-butts, so this guy has found the perfect solution. Skinny jeans on the inside, loose jeans on the outside. That could be a hook to a song.
Ultimately I don't understand sagging on a functioning level. Have you ever seen someone running from the cops in sagging pants? 90% of them would have gotten away if they were wearing track pants. They've got their keys and wallet falling out of their pants as the fabric flops around. It's a bad plan!