How exactly does the money making process work? You buy some cryptocurrency for a certain price then sell it for a higher price and the difference is the money you've made? This would mean that the money you've made is still in terms of cryptocurrency. Then can that money be converted into the whatever kind of cash your country uses? How does it work?
So it works like you described, and the conclusion is either through exchanges with a commission, or through trusted people. In general, those who want to get a lot going for long-term retention of their investments, on short-term ones are very risky.