It depends on the token you invest. Digitizecoin, for example, gives you the option to buy in a store using dollars and instead of taking coins as a change, to receive tokens. Then you can exchange them for other cryptocurrencies, or by using them instead of money. Some ICOs have brilliant ideas, however, if people don't support them they will fail. But if they will be successful and you bought them early, you can make a small fortune.
You get a token from ICO will definitely be sold, and the buyer who bought the token from you, the token will be used for what by the buyer? , and is there any other functionality of tokens other than for investment?