Interesting question. Theoretically, any business can be profitable with good business systems management in place. People say restaurants have the highest failure rate (they don't actually); however restaurants have the advantage of regular cash flow. So "profitability" or "easy money" aren't really the question.
Perhaps asking which business ideas are the easiest to setup business systems to ensure profitability. Splitting hairs, I know, but it refines the question in a way that will help you make better informed decisions on which business venture to explore further and help you build the skills to make any business a success.
I also believe life should be wonderful, so potentially viewing the world only through the lens of financial success might be the wrong approach. We all need money to have fun, but why not have fun making money and doing something we connect with and believe in? (woo woo, of course, but at the end of the day, we all want happiness.)
