If every investor, like you, will sit and wait until a sufficient amount of money is collected in the projects wallet for its implementation, ICO may end and you will be late to make your investments.
the risks of the investor are very high and everyone is afraid of losing money, especially novice investors, and everyone wants to check the project carefully
That's it in order to encourage those who are not afraid to invest before anyone else, developers usually use bonuses and discounts on tokens prices.