Another example of startup hubris. Much like Uber and AirBnB got started (and in many cases, continue to operate) by flouting regulations, Robinhood thinks they're being innovative, when they'll really just hoping they can get big enough that they can buy or bully their way past the rules. At least long enough to get acquired. It might work, but in this case, the people most likely to get screwed are the customers.
Uber and AirBnB both flouted primarily city-level regulations that are tough to enforce against external players, and where they broke larger rules it was by pushing vulnerability onto their service providers (e.g. drivers who assume Uber handles taxes like they're direct employees). And at least some of the regulations they ignored were so obviously protectionist that "look, we're breaking the law!" could actually form a selling point. (Which let them redirect focus from more popular rules like property hygiene.)
Robinhood is tangling with national financial regulations, which for all their loopholes and weaknesses are made to take on far larger players with a history of bad behavior. Meanwhile, the rules they're breaking are pretty much all directly tied to consumer protection, so it's going to be mighty hard to run an ad campaign to raise sympathy.
It reminds me a bit of Theranos, actually - "fake it till you make it" wasn't novel, but they neglected massive differences like offering an unsustainable service versus signing unfulfillable contracts, or failing random website visitors versus crossing major corporations and the DoD. It's like a clumsy new lobbyist offering a bribe instead of making a campaign contribution and expecting consideration; the dynamics might be similar, but the gap in execution could easily destroy them.