Part of that decline owes directly to YouTube policies about monetization. For many years, and until very recently, YouTube would not allow creators to monetize videos with queer content.

So while some cis/straight creators were making good livings or earning good side money from their work on YouTube, queer creators had to work for the pure love of it, or leave.

Many left.

Life is busy and hard for most people. Few of us have time to devote energy and passion to projects purely for the love of it.

YouTube still discriminates, sometimes very badly, against queer content creators but at least their nearly automatic demonetization policy has ended.