You can always choose not to use Youtube if you hate Ads so much.
It is a monopoly doesn’t mean it is a public utility. PG&G has a monopoly in electricity in my region, does it mean I can steal the electricity because I don’t like PG&E and I don’t have other options?
All tv channels have either ads or you need to pay, how is this different than what YouTube is trying to do?
If you pick up a free newspaper on a commmute, or, say, a community "What's on" sponsored by ads, does someone look over your shoulder and insist you read every ad before they let you turn the page?
But are you asking in good faith? Or are you asking because you want to get to a point where you use a service that costs money to maintain and yet you don't spend money or view ads but you still feel ethical?