I think he meant don't invest in others businesses, start your own. Depends on whether you're good with money and bookkeeping, etc I suppose.
Yeah indeed starting your own business isn't a easy thing which you can do in one two three, you need knowledge for it and a capital aswell.
I wouldn't start my own business, way too much working hours and risk for me to be worth it but ofcourse you could live very wealthy if you succeed.
If you start an online business instead of a physical business costs tends to be a lot lower besides it doesnt need to be an awfully big enterprise, for example you could begin by setting up a faucet and earning some bitcoin that way.