That's part of the reason for some of them but ultimately I think the primary reason is boxers are just naturally more cowardly and reluctant to step out of their comfort zone. In MMA it's the norm for the best to fight the best and if you take a loss Dana and co will throw you right back in with a killer in your next bout in a genuine 50-50 fair. And if you suffer back to back losses they'll throw you right back into another genuine 50-50 fight against a killer. And if you suffer three back to back losses you'll either get cut or thrown to the wolves yet again in another genuine 50-50 affair against a killer. This fosters a much more masculine warrior culture, the type you only really find tin this day and age on the mean streets of Britain, in the travelling community (gypsies) and the mountains of Dagestan. Take Chris Weidman and Tyron Woodley for instance After losing his title to Luke Rockhold they three him in with Yoel Romero in his next fight. Then after losing to Romero they threw him in with Gegard Mousasi. Then after losing to Mousasi they threw him in with Kelvin Gastelum who he beat. Then they threw him in against Ronaldo Souza. And then after losing to Sousza they threw him in against Dominick Reyes. Absolutely brutal matchmaking. After Woodley lost his title to Usman they threw him in against Gilbert Burns Then after losing to Burns they threw him in against Colby Covington Then after losing to Covington they threw him in against another beast in Vincente Luque who has bricks in both hands and his chin I hear a lot of boxers say they want to step over into the MMA world but very few seem to be willing to do so when it comes time to back up their boasts. Floyd promised Sugar ''Money'' Mac that they would have 2 fights - 1 in a boxing ring, and the second in the Octagon. He would've earned an absolute mint for both but only one of them was man enough to step into the other's domain which all but guaranteed them a loss. Sugar ''Money'' Mac taking Floyd's ass to slick school for four rounds while he still had air in his lungs is unquestionably the single greatest event win in the history of sporting competition. But that's J-Paul money, Kirk. J-Paul has completely revolutionized the game and everyone and their dog wants a piece of the J-Paul sweepstakes. We're taking about someone who walked away with over 10 mill for their second pro fight for goodness sake. In fact, it was his second fight ever because he's a YT sensation not a fighter. The guy completely exposed basketball for being a sport of elongated wimps, he's about to expose the world of MMA for being an inferior combat sport in his next fight against Ben Asscream so god knows humiliation he's going to heap on the infinitely more inferior sport of boxing when he's finished exposing the world of MMA.