Its probably as ethical as gambling companies exploiting their users, there's long terms effects for both getting hit in the head, and spiraling into debt because gambling companies want people who are addicted to gambling on their platform spending money. Of course, it is horrible that boxers to sustain injuries long term, and there probably needs to be more done in that regard. However, they do know the risks, and they do sign on the dotted line. The issue is, this is most probably due to a lot of them coming from disadvantaged backgrounds, and trying to change their lives.
The consequences may be the same sometimes, but gambling companies still seem more ethical to me. All they want is to earn money by means of attracting people, and every business in the world is like that, in boxing, on the other hand, it’s not money that most people want (many watch just for fun, no betting involved), but the game itself.
I’m not saying that it’s ok to get people hurt for money, but at least there’s a purpose in there, maybe the companies even feel sorry at the end of the day
In boxing people literally want one man to smash another, and they enjoy when that happens while getting nothing in return.