Because interest rates were historically low for the entirety of YT’s existence until recently. You’re seeing this happen with multiple platforms and companies suddenly caring way more about being profitable.
It was clear from day one of low interest rates that those wouldn't stick around forever. This business model is a pile of s** that breaks itself.
It appears as if the most 'successful' business people actually don't think a lot about any kind of sustainability in their decisions. It's just about quick growth. And when push comes to shove, they wine that they aren't able to pay the bills anymore, because of 'evil' users who don't want to watch their crappy ads.