Buy or develop your own time machine and go back to 2008 and mine BTC on the computer at your mothers house in the basement
Work hard and save up for the future, and also invest something.
I guess I need to state my opinion in terms of bitcoin as I strongly have more faith with bitcoin and it's growth. When mass adoption is possible for bitcoin among merchants and buyer then the price of one bitcoin will hit the moon. So, if we hold small amount of bitcoin also will make us rich.