Maybe not but I’d be against boxers or MMA fighters betting on themselves as well. Betting on yourself is also different than betting on a match you’re not involved in, but I think it’s easier to just have a blanket ban on betting instead of all kinds of exceptions.
It’s also not like you’re depriving a player of something meaningful if you don’t allow them to bet. I don’t see the upside of allowing it, only downsides.
2 teams at the same time can be one of the best of all time. It’s not a direct comparison but look at Barca and Madrid during the 2010’s for example. They were a very influential team in football history, just like Sacchi’s Milan.