Gambit, Marvel's new bad guy

Being a Marvel comics and trading cards collector growing up, learning about Gambit shifting sides from superhero to supervillains is a bit shocking. A bit shocking because it's clear, back then, that it IS Gambit's boots, he must be examining, like vultures, the deathland of X-Mens, on one of Marvel Universe Mystery's trading card series.

A post from Wizard Universe cleared my hypothesis.

Move over Magneto, hit the deck Doctor Doom—there’s a new breed of bad guy in the Marvel Universe. With the aforementioned pair lying low, the Kingpin ousted from power and most of the heroes focused on battling one another, a motley crew of also-rans, new faces and long-dormant threats has emerged to fill the vacuum of evil...

...THE MARAUDERS
The X-Men have found themselves under siege of late not only from familiar foes, but once-trusted friends as well. The Marauders combine the worst of both worlds, with former teammates like Gambit, Mystique and Sunfire standing shoulder to shoulder with sworn enemies Exodus, Random and Scalphunter.

“Gambit is going back to his roots in the worst possible way,” laments X-Men writer Mike Carey. “Hanging with Sinister and the Marauders—it’s like ‘Mutant Massacre’ all over again, except this time he’s got a really twisted agenda that’s all his own.”