In that case, the only incentive they have for you to fail is to pack more gym memberships in the same square footage. Still, I think as a perverse incentive it's a lot more indirect.
Exactly, while they can benefit from having fewer people go regularly to offer a better experience to those who do, churn is still a gym's biggest problem, it's why they lock up longer contracts and why gyms have trainers available and regular progress reports, to enhance customer LTV.