Well, if it would be that easy, everyone and their mom would be already Youtube millionairs. Since this does not reflect reality, there must be a flaw in your method don't you think? I don't doubt that you've earned the amount you stated above, I just think you are drawing the wrong conclusions from that.
How are visitors supposed to find your videos, if you don't do anything (e.g. don't add views, likes and comments) to get them ranked? If your video sits on Youtube page 21 for a certain keyword, nobody is going to see it.
So let's stay with your example and say you just posted some audiobook videos on Youtube. You further said you copy videos from others and re-up them. That means your videos aren't unique and you got some competion. How do you outrank them? By doing nothing? If that's the case, your competition seems to be so weak, that it just takes a video with a seo-optimized title and description to rank it. Of course you now can say, I did nothing and got my videos ranked. And that's totally true. But, and that's the point, it has only worked because your competition was so weak. Try the same in a highly competitive niche and you'll notice that it won't always work this way.
People bot views, likes or comments for a reason. The reason is that it works fine. Do you really think people would put all the effort in it if they would not see any results?
Untrue. Nothing at all happens to your adsense account, if your Youtube account got banned. Adsense bans you if you click on your own ads and stuff like that, but they don't care about strikes or bans on your Youtube account.