Ppl go crazy with any type of hobby, it consumes them and they get into a “problem” of collecting, and develop obsession with any topic they get into.

However, more than a single pair is normal. For example I have one full size open back headphones for enjoying music at home, one high end iems for listening on the go and in bed, and one semi-wireless for gym and cycling cos of convenience that I use with smartphone. Over 3 pairs for different purposes and I can genuinely see no point, but as I said, ppl get consumed by the hobby and that is true for any hobby pretty much.