Even when ad blocking extensions work, it's only for browsers. If you're on Android you can install hacky modified apks, but YouTube breaks them every once in a while and then you're waiting for an update and having to go through some patching process again (I have to do this with YouTube Vanced to watch YouTube on the cheap Kindle Fire I use exclusively for YouTube in bed). If you're watching on a smart TV YouTube app or Apple TV or something... I assume there's options, but you're again gonna be wasting so much time on maintenance and keeping things up to date in the ad-blocking arms race, I'd rather just pay. And I don't know why anyone should expect YouTube to be infinitely ad-free and payment-free forever. All that storage and data transfer ain't free.
Far from it that I'll defend Google, but I don't know what's so special about YouTube where it's the one service people use more than anything else they pay for, but they won't pay for it.