There is an easy route to increased wealth if people will take it: maximize your contribution to your 401(k). This is especially true if your employer matches your contribution. Once money is in the 401(k) it gets invested in (drum roll) stocks and bonds. The profits are also reinvested. And none of this money is taxable so you get to be one of those rich people that doesn't pay taxes on his money.
The thing that stops most people is they fact that it takes twenty years or so for this to start showing significant gains. You have to be ready to play long ball, this won't show immediate results. Gratification is delayed, something Americans aren't good at.