Robinhood offers free trades on anything in the Stock Market. Literally free, you can't beat that.
> There's also a law that requires you to be big capitalist before you can do early big investments right?
That's not the stock market. That's venture capitalism. The stock market is literally open to everybody with an internet connection from a variety of well trusted sources (RobinHood, E-trade, TD Ameritrade, Vanguard, etc. etc.) and a variety of pricing schemes. ($0 for Robinhood, although it seems like their execution is not as good. You get what you pay for afterall)
Furthermore: the stock market is regulated. The National Best Bid and Offer (NBBO) system in the USA ensures that everyone in the USA pays relatively consistent prices, or at least more-consistent than BTC / ETH. Unlike ETH or BTC, no one is going to steal your money Mt. Gox style as the SEC is a strict watchdog.
You get no assurances with Eth or BTC. Coinbase has different prices than Bitfinex. And some of these exchanges look like they're running scams (ie: Bitfinex's support of Tethercoin).
I think more "plebs" have been burned by Mt. Gox and other such failures in the cryptocoin marketplace. Its a hugely unregulated, and highly risky market. Cryptocoins are just not mature enough for mainstream speculation yet.