Sex appeal. Peloton is built on sex appeal. The instructors lead workouts wearing makeup, jewelry and bikini tops (well, the female ones anyway). Vox has an article [1] looking at SoulCycle and it sounds similar: instructors were good looking and exhorted to be incredibly thin. That said, it's a great way to get a good 30 minute cardio workout in.
[1] https://www.vox.com/the-goods/22195549/soulcycle-decline-reo...