I think there are many possible benefits by buying on ICO. What is clear is: You help companies launch their products. There is also an opportunity to make profit selling ICO tokens after you buy them.
In many cases, crypto tokens released during ICO are sold at a fixed price in the amount of Bitcoins, eth or US dollars. The price is not supported by anything except the buyer's community trust in the development team to release this product successfully at some time in the future, so usually the token price is quite low on the ICO. After the project is developed and launched, the token value becomes secured with the product that is operating and real. And this phenomenon will lead to price increases and investors can sell their tokens for substantial profits.
However, keep in mind that not all benefits are guaranteed. If the ICO fails, all contributions will be returned to the sender. Even if it works, there is a possibility that the developer cannot send the final product and the token price will never rise. This is the risk that all ICO participants must take into account when they decide to contribute to any ICO.