It’s just gay culture with an anime internet culture framing. We can’t be cute (young) forever. Gotta become cute (ancient) instead. There’s also a bit of pathos involved for the gays that stayed in the closet for very long.

Feminine catboy growing old and being inflicted with old man

As depressing as it is, middle aged can be considered “old” for trans folks because of the low amount of trans people that make it to actual elderly age