The way you ask tells me you're not big into investment lit and that's okay.
Summary version:
Stocks aren't even available to you when they have the most potential reward--because that is also when they are considered the most risky! There are legal controls to allow only "qualified" investors (people with net worth of $1,000,000+ AND A LOT of education, usually) to invest in those. It's bull**** (and self-serving for the already-rich, which is the point) but is what it is. And it's usually something that means "public" stocks are...well not necessarily worth buying into (unless you want to wait around for 70 years for huge gains, assuming the market will keep running-up)).
So you option is DOING business. Or buying into one.
That means handing-over money to some SBO or new startup that is very, very likely to go bust--unless it isn't, such as it's very simple, or something the SBO is hyper-familiar with and can do impressively (every time).
There are actually A LOT of opportunities in the SBO/new startup space (NOT in "tech"!! which is HYPE! I know, I'VE HELPED BUILD SOME OF THE BIGGER TECH STARTUPS!!!!) where people AREN'T aiming at BILLIONS--but just at steady enough revenues to impress the more-ordinary people.
I've been working to crack *a* nut (among a handful that are there) for a while due to the legal barriers to fair and high-reward investment (despite higher risks) and I'm getting more and more comfortable with the domain but still have a lot of research, and potential R&D, to do--and professional help to pay for to get things moving even just for myself.
The tricky bit is identifying where the actual opportunities (vs. guaranteed failures) are. Once someone has a handful ID'd then depending on jurisdiction, even without trying to do drop-shipping, wordpress site or SEO scams, etc. (that some look to trying to gain buckoo bucks quickly), it's reasonable to think an investment could return from 2-5x the ordinary wage-earner's daily take-home from investment, without the involvement of some capital contributors.
That non-involvement (in jurisdictions like the USA) is actually key: lower tax rate AND time free to...focus putting money elsewhere that will reap returns. The lower tax rate is called "passive income." Invested THROUGH a business and that income goes back to the entity allowing re-investment, and possibly then avoiding (note "av" NOT "Ev") taxes because the USA (and generally, western) gov(s) WANTS people to invest and grow the economy.
Then there are other factors but this is about to go too far along for "Summary Version."