Training people is tedious as shit, boring ,either you or your gym needs some sort of liability insurance , and if you're in a gym a lot it's a bitch waiting around for some fckwit to show up
Smart IFBB pros either have a supplement shop, inherited wealth, or you just 'work hard' like branch and money is just there
Personal training is busy work - why most trainers don't train hard or are really big dudes - you have to be personable to attract and retain clients, most aren't ,you have to wait for people to get up or get off work , schedule is shit , can't eat and get enough meals in, and when you train and bust ass you don't want to stick around for some skinny bro with low T and HRT test thinking he's superman to come in and tell you he's going to be your size after 6mknths training with you so he needs no more than 12 sessions ---
Easier to sell fart powder and bro diets online , as would be to charge old dudes for 'fruit bowls ' and 'goatses'