Why might a self-aware gym buyer choose monthly even knowing pay-per-visit could be cheaper?

Answer: It acts as a commitment

It acts as a commitment ✓ — Right. A flat monthly fee can be a self-control tool: paying in advance makes skipping feel like wasting something already bought. That does not mean it will be cheapest; it means the buyer may rationally pay for pressure on a future, lazier self.

It adds social pressure — Not quite. Social pressure can help when friends, classes, or trainers are involved, but a plain monthly fee can work without anyone watching. The mechanism here is self-imposed financial pressure on future behavior.

It signals fitness identity — Not quite. A membership can signal a fitness identity, and that may feel good at signup. But the economic reason to choose monthly despite possible overpayment is pressure on future behavior, not merely owning a fitness label.