in the end, you’re leeching off a service you enjoy.
I don't think that's a fair or true statement.
For one thing, the "service" here has risen to a point of ubiquity that it's a de facto public space. Everything is on YouTube – legacy media channels, individual enthusiasts, alternative media outlets, the worlds of tech, fashion, politics, sports – you name it. If you were deprived of all access to it, you would have a qualitatively poorer access of what is going on in society. So it's not equivalent to a traditional service like a trade.
For another, blocking ads is not merely refusal to pay a fee of some kind. Advertisements are cognitively intrusive, designed to affect your willpower and decision-making, used to track and control your behaviour, compromise your digital safety, and turn you into a product for companies to whom you do not give your consent for the opportunity to be exploited. Blocking that system of "payment" is not simply prudent but right, and the choice between paying a monetary fee or being so exploited is not a fair choice at all.
Not quite sure how you got to the point you did there. There are different ways to advertise – billboards and TV/radio adverts, e.g., while often odious, are something you can more easily divert your attention from and which are not tracking devices or the product of turning you personally into an item for sale. I dislike them and would prefer a world without them but I don't think their being attached to organisations in and of itself ought to deprive those organisations of income.
That is apparent.
This is called "begging the question" as a response to me – I've called into question exactly both your premise and conclusion, for reasons you've not actually engaged with, and then you've re-asserted them. You have assumed what you've set out to prove.
(1) it is not simply a product (or service – you've changed tune there), for the reasons I've already outlined. Its use and availability is not analogous to something you can pick off the shelf or pay a tradesperson to do for you. (2) therefore, the question of paying for it (and how) demands different kinds of answer. In the country I'm from, e.g., healthcare is a right and not paid for, neither is early-years education up to 18, and so on. Both are "products" or "services" in some sense of the term, but to speak of payment here is complex and the answer doesn't simply carry over from thinking about normal products/services.
This can only be a disingenuous response, surely? Rather than engage with the criticism of the nature of modern internet advertising and how corporations use it to affect people, you'll just summarise it as "scary words".