what are you going to do when you're broke at 9:10?

Only 1 share can be bought or sold every 5 minutes. In some fairly naive simulations this system was ran against, it would take weeks and months to fall below the 25k mark.

Voting weights can be introduced to mitigate spamming and round lengths can be adjusted to mitigate other issues.

It could turn out a complete disaster, but it will be a disaster in slow-motion.

The transaction fees will kill you, rather than the spamming of penny stocks.

Using the Robinhood App allows trading with zero fees. Additionally, Robinhood has a feature called RobinhoodInstant where trades are settled immediately so funds don't get stuck in pending settlement.

Nice. Zero spread too?

Unsure, though would guess probably not. They apparently have a nontraditional method of executing orders, see https://archive.fo/hf0rt