But this come with some risk, then you need put in balance, safe trade = low profit risk trade = big profit.
Can you explain what you exactly mean? Perhaps that I understand you wrong. But basically, it's like this: Low risks equals low-fair rewards. High risks equal high rewards.
I think hes referring to forex trading i guess since in that trading style it trully matches. In making risky trades increasing lot size on a open trade is considered risky but same as bitcoin/altcoin trading risking too big amounts on a single trade on altcoin would surely give you decent amounts when it turns in our favor.