An overnight millionaire is someone who goes from barely making enough money to keep up with his expenses and still has a few extra to buy a nice car or to go on a cruise. He has a lot of extra money in his account, but the government won't let him take it out. He waits for tax season to pass, and then he pours out a ton of cash to make ends meet.
Now you might be thinking that this is not a really viable way to run a business, as you have a full-time job and have to put money away for retirement. But that's okay. The overnight millionaire has this luxury because he isn't having to live with the day to day expenses.
All he has to do is stop working to spend all his money as he wishes. Instead, he has to stop working until he is retired.
Of course, there is a risk involved when starting your own business, but the risk is reduced if you're investing in the overnight millionaire system. Investing in the overnight millionaire system is the safest way to invest, so if you have that luxury then you should use it. The better investments allow you to make large profits over time but at a smaller risk.