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 investing in other businesses is more profitable though making your own is more profitable after a while but i wouldnt have the balls to make one revolving around bitcoin because if bitcoin dies your company dies and that's a hard hit but with usd you are sure it wont die out.
Indeed investing in something that has a stable so as not to be higher risk than investing against things that have prices fairly stable and highly needed by most people in the world. But it's all also have a negative effect and positive, so we can choose a more suitable where things on ourselves.