For me, it's social dancing, specifically West Coast Swing. Because while there is just social dancing, and some who only do it, there's a bit of a culture of competition, and it has its own governing body for determining where you place in competitions, and when it does sound like a cult when described.
All of them, but also hobbies don't have the support networks to take care of vulnerable people as a hook, so it's just the negative parts of cultish aesthetics (e.g. 40k players don't provide much housing or affirmations in order to draw people into 40k)