I’ve resorted to opening my page editor and deleting entire blocks of ads from some pages to get it down to something readable.
Presumably they think some people might want the channel enough to pay cash for watching it. Probably not most, but as @Der_Trihs says, if you’re not a paying customer they don’t care.
What percent of YouTube regulars who don’t pay even play those videos? It has to be minuscule to the point that they have a million better things to do and it won’t drive anyone away anyway. They certainly won’t have video only ads that no one will watch. Why would an advertiser want to have that be a thing?
Your choice is either to pay for the content or create your own track on a thumb drive.
But (in a broad general sense) they don’t want you on the platform if you’re just consuming the content without generating revenue.
Supposedly calming content that is interrupted periodically by loud ads is of course self-defeating, but that’s a choice made by the channel (it may be the only choice they feel they have due to financial constraint, or it may just be that they don’t care enough to curate their content properly).
Tp a large extent content creators make a deal w the devil when they use YT as their distribution channel.
The stories of how YT screws the creators and screws the consumers are legion.
Maybe so, but I sometimes get the impression (including in threads like these) that some people think they’re getting screwed if they’re not getting something for nothing.
How about one or even two non-skippable ads at the beginning of an overnight video? That’s perfectly fair and fine. But at darkthirty A.M. it’s a taser.
How does fair enter into it? How do they distinguish an overnight video from a regular long video? Why should they even bother with that for a non paying customer?
If YT or any other media service offered a program of unlimited use, zero tracking, and zero advertising for a single fixed low monthly or annual fee I’d be all over that.
They assume the demand doesn’t exist so they offer only ad- and tracking-laden options.
I can’t buy what they won’t try to sell.
I doubt I’m alone in this desire.
I would think that “Sleep Sounds” and being eight hours or longer might be a hint. And every non-premium channel on YouTube is paid for by ads. On the theory that you catch more flies with honey than with vinegar, one might suppose it would pay to not specifically ruin a video with misplaced ads.
I’m not sure what you mean by “tracking.” It is possible to turn off your YouTube watch history.
YouTube is a computer. Zero humans at YouTube know that channel exists, much less that it would benefit from special ad treatment.
The only human in the equation is the creator = channel owner / manager.
YT may or may not offer switches that human could flip to provide a no-middle-ads experience. But if not, that creator has substantially zero ability to lobby for same.
By design, YT is oblivious to all input except answers to questions they choose to ask of their 3 constituencies: first, advertisers; second, creators; and third, consumers.
Hint: your interests in group 3 don’t matter. Except as tie breakers versus groups 1 & 2.
I would think that the most sophisticated marketing people and AI software on the planet know much better what works for them than your weird idle speculations. They have many billions of videos and aren’t going to have someone write code to suss out which are sleep videos to make it easier on deadbeats who don’t pay subscription fees.
Not quite everything you want, but Nebula (https://nebula.tv/) at least is owned by a small group of content creators and shares profit with the rest. It’s mostly documentaries and educational channels, though, so probably won’t have random sleep videos.
There’s also the “Calm” app for subscribing specifically to sleep stuff.
“Deadbeat”? 
If YouTube wants to change their entire business model to be a subscription streaming service, that’s their call. But offering free-with-ads viewing for the vast majority of its millions of online videos has been the majority of their service. What I’m wondering is what the hell is the logic of deliberately enshittifying their service in a way that actually undercuts why anyone would want to view a sleep video on their site at all.
Their model works for their ~15 billion videos less a few hundred sleep videos but only for non subscribers who listen to sleep videos. It wasn’t intentionally screwing over your tiny cohort. They’re completely unaware of you. It’s such a minuscule use case that they aren’t going to spend resources fixing this “problem”.
I don’t quite get this issue as using Brave there are zero ads on Youtube. 
That sounds like a question for whoever posted the sleep video.
It does. Midroll ads are entirely optional.
Cynically, because you’re not worth anything to them if you’re sleeping.
True, but does your channel not also need to be above a certain size to have any control over ads?