There are wuite a few people earning $100 a day on this furm. If you refer to therecent thread asking daily income, quite a few people voted for the above $100 a day. I am not sure whether they are being trutful or not, though.
This is true you need to have a site where you are the expert in the subject. Your niche ( subject ) needs good content so stop reading and go develop your site. Don't worry about what makes the most money you will eventually get there.
So how did sharing your site URL with others get your banned? I don't undestand - Google don't ban people because they tell other people about their site... There are a LOT of people on these forums earning more than $100+/day! There are a LOT more that are making $100+/day but are smart enough not to disclose how much they are earning.