>As soon as you actually try and sell your coins into the market, you see that you've eaten through the order book and driven the whole market down 10 percent. With

There is no way you could push down the market 10 percent today. Maybe back in 2011, or maybe in one of the lesser known cryptocurrency markets. But in Ethereum, you could unload a huge number of ETH and the price wouldn't budge. I'm assuming of course you're not an institutional trader, in which case of course Ethereum trading volumes are insufficient to absorb large trades without significant price movements.

>Smart contracts are seriously entirely useless unless you solve oracles.

Even a basic cryptocurrency transaction (sending ETH from Account 1 to Account 2) utilizes smart contracts. Having Turing Complete script evaluation just means the range of smart contracts possible becomes larger. So for example, schemes like Lightning Network are possible with Ethereum, without any changes to the protocol.