Its impossible for a boxer not to consider on making money and some would really be focusing on building some hype and some would just have those words casually since they do know that they can still purse out without the need of those actings and trashtalking towards the opponent.
But some boxers are no choice sometimes so they will still accept small paychecks just to have a fight and build their names.
Casimero is a champion and I think he's already earning well every fight. He just wants more than his usual which might not easy to be granted since even for a champion, a name must be popular to make a market hype. A good PPV history is also a must so boxers are doing something interesting to sell the fight and that involves trashtalking the opponent.