Why/how did so many genders suddenly start existing in the last couple years?

So I know you should refer non-binary or people I am not sure about as they and be as ambitious as possible. Some people don’t want to conform to the norm, which is fine, more power to you for being yourself.

But apparently there are more unique gender pronouns than there are letters in the English alphabet and that just seems silly no matter how you slice it. Seems like they are being made up on the spot to express individuality rather than identity, but I would like to hear some reasoning for it.

Edit: just a quick thanks to your answers, they are all interesting to read. I can’t respond at the moment but they are all helping me get an understanding.