With all respect, do you have a source for that? I thought Alphabet was losing money hand over fist on YT before they started being so aggressive with the ads.
Let's for the moment assume that you are right, then they shouldn't have bought it in ... 2006, all of 17 years ago. And if they are short of money why are they pushing more and more junk on people? Let's start with switching off autoplay by default, limiting videos to 640x480, and offering creators to pay for the hosting so that their video can be shipped, just like I pay for the hosting of my web servers.
If so it's not just the infrastructure cost which itself is not trivial for a site like youtube.