Unless they're really, seriously wasteful with the soap.. there's no chance a gym is losing money on a heavy user
Right now all these AI subscriptions are priced like Planet Fitness, but they're used like Equinox. They're hoping that the new a la carte offerings will move their pricing more in that direction as well.
US gyms might be vast warehouses but in the UK, most only have a couple of benches, couple of cages, one set of db per denomination above 20kg etc. They require working-in and consideration for others.
A couple of unapproachable "heavy users" doing 3 hour sessions across peak hours can ruin the workout for dozens of paying members needing a few min per station for ~5 sets.
It might also be a euphemism for "dickhead" who also tend to be "heavy users". Those that damage, hoard and don't share equipment and repel other customers on many levels besides - threatening, lecherous, loud and smelly.
Doesn't even need malicious intent - can be weirdo bores, forever talking at victims while doing a routine that makes absolutely no sense besides camping on equipment for half a day... 100 sets of incline press 7 days a week... what are you even doing to yourself fella?