I never “got it”. It’s just a brokerage like etrade? Those places charge under ten dollars per trade. What’s the big draw for zero fees? It’s not like you buy stocks that often.
They also have super cheap margin loan rates.
The zero fees might still be nice if you want e.g. to contribute every paycheck; but an old-fashioned Vanguard mutual fund would be just as good for that, or many brokerages have zero fees for specific classes of ETF. The only advantages that I'd see to Robinhood are (a) no minimums, and (b) pretty UX.
But beyond that, Robinhood has a really easy to use UI compared to platforms like TDAmeritrade. It's not only much easier to make trades but also see information like how much dividends I've earned, whether a company has hit their earnings, etc.
Robinhood also lets me invest any money I transfer from my bank immediately. There's no 3-5 business day wait. That said, I'm not sure if this is feature available to everyone or only those on Robinhood Gold.
You accumulate a “book” of end customers, usually from a particular demographic, for the purpose of selling to someone who doesn’t have that demographic. Versus flow (e.g. exchanges) or asset accumulation (e.g. ETFs) businesses.