Go for a business that any idiot can run - because sooner or later, any idiot probably is going to run it.
In the long run, it's not just how much money you make that will determine your future prosperity. It's how much of that money you put to work by saving it and investing it.
What makes stocks valuable in the long run isn't the market. It's the profitability of the shares in the companies you own. As corporate profits increase, corporations become more valuable and sooner or later, their shares will sell for a higher price.
Invest in businesses any idiot could run, because someday one will.
In the long run, a portfolio of well chosen stocks and/or equity mutual funds will always outperform a portfolio of bonds or a money-market account. In the long run, a portfolio of poorly chosen stocks won't outperform the money left under the mattress.