if you want to trade with low risk, trade a coin with high marketcap like ETH,XRP,DASH. those are quite stable.
or if you want to trade with high risk, choose any low marketcap coin, higher the risk higher the profit
but many of the low cap coins turn out to be scam, the risk is too high.
i think that is why he said higher the risk, higher the profit. with low cap coins spread must be high, and even with small capital we can get more profit than we trad in coin which the price stable.