One of the main reasons of altcoins is the incomes you can get and the profit. You invest, you hold, and then you have the profits
no. Its not. The main reason why cryptos are built is because the developer wants to deliver a service (a unique service) that uses the power of blockchain technology . however some people mistakin cryptos as an earning oppurtunity in order to earn a profit because cryptos can also be used as an asset aside from their primary purpose on which is a currency or medium for thier service.
the actual use of altcoin aside from trading is for payment system/method. Trading or investing is only for a secondary use.