And then came USADA and Mr Velasquez.
Why none of the boxers step into the octagon? Because they know they would get wrecked. It just so happens that boxing promotions pay more, so boxers can always use that as an excuse. And they do. And they are right.
Only way to avoid this embarrassment, is for UFC to start paying their fighters more than boxing promotions do. Then we can have Francis Ngannou calling out Anthony Joshua and Tyson Fury to a real fight for the real money. I guarantee you that all of those boxers would keep their mouth shut and none of them will ever step foot in the octagon.
But yeah. It aint happening.
The madman training Velasquez did for the JDS fights pretty much destroyed his own body so that trilogy cost him his own career as well.