Nah it's mostly because alot of fighters these days never think of the long term, only short term. You have fighters sitting out for months "waiting on a big payday" so they can get paid $10 mill for a fight. When they could have just fought 3 times a year for $3 mill each fight. The latter is the more common sense one because you get paid similar and you have more visibility with casual fans
Perfect example was Keith Thurman. Dude out of his own mouth admitted to turning down multiple fights because "the money wasn't enough". And that he won't get in the ring if it's under a certain amount, etc. When he's not realizing that fighting multiple lesser money fights will make him sharp, risk less injury, and add more visibility to his fame. And isn't it ironic that his "big payday" that he was supposed to get this year against Fundora was cancelled because tickets weren't selling
Only a handfull of dudes getting 3ms a fight and even then i dont think the promotional companies have budget. TR was losing money for example
. I think up to the time of the writing of that book, which was before the second Dempsey-Tunney fight, boxing experts still saw Johnson as the best Heavyweight champion and that he was too skilled defensively for Dempsey.
