Someone mentioned the CPM is much higher in the travel and finance categories, so the earning could be 2/3 times more. However, you are right, most people have a dual strategy where YouTube drives sales to their own products usually from my research.
Some YouTubers have mentioned it's just some coffee money and a hobby for them, but hard to tell for sure.
One thing is for sure, you need to add value to your content to gain any traction and rewards, the same as on Hive.