They are called PARTNERS, SILENT PARTNERS, PRIVATE INVESTORS, VENTURE CAPITALIST, ASHTON KUTCHER, what ever the F you want to call them.
If your business is making money hand over fists, there are always people willing to lend you a private stake to reap the rewards.
It is an easy pitch, "Don't you watch SHARK TANK?" For F sake.
"Invest in us now so we can reach a certain goal to expand, for which we will give you a certain stake in the company."
Those that have NOTHING or can prove NOTHING don't seem to get very far in real life or on the show.