Forget make money products, most of them are simply fraud products.
There is serious money in mainstream and it's so easy, it's stupid.
Look around you, anything you use on a regular basis, electricity, mobile phone, insurance, software, computers, services, you name it. Each one of these things provides you the chance to get between the supplier and consumer and take a cut.
You need to choose your niches carefully and use proven tools like
Market Samurai to research niches within markets. Do your homework and you will find numerous ways to offer mainstream services/products and take your cut.
I have an online electricity supplier comparison site for Melbourne, each month maybe 20 or 30 people sign up to one of the plans. I get 5% of their payments for life, a few hundred customers a year multiplied by 5% of their electricity bills adds up quickly.