I saw your post on another forum too. I didn't reply there because this idea isn't easy as it sounds. sounds good when you think about it. That's not how things work.
managing 100 websites manually is not an easy task. you will end giving up everything.
earning 50$ per website means you're using shittiest ways to promote your website. If you use a better method you will easily earn more than 50.
You better build a PBN with 100s of domain to rank 1 or 2 authority websites. That is more interesting and less stressful. And Will bring you more money than you think.