Causation vs. correlation is always a fun topic. (We all know that places with high crime rates tend to have more police and therefore police cause crime aka the Batman Paradox.) It’s interesting to see what kind of illogical and misguided decisions can be made without correctly understanding what is the cause and what is the effect.
Similarly there is the issue of self-selecting groups. This is the phenomenon when you are trying to understand who frequents your business or which people are most likely to behave a certain way. Just because one group is the focus currently doesn’t mean that others wouldn’t or that you could get the same group again. Sociological effects have a role.
People like to hang out with similar people. If you have a few catalysts from a group and they draw in others – not because of you but because of them – you may suddenly think you’re seeing a trend you can capitalize on when in fact no such trend exists.