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?
If you are trading altcoins, it should be traded to bitcoins first before it is converted to fiat currency. Depending on which country you are in there should be like online wallets wherein they buy your bitcoin and exchange you directly with fiat currency depending on what is their current buying rate. Also check if they accept other alts such as ETH directly to fiat currency and that is the time you can take out your profit as cash.