What does the price of the coin matter to the project after the ICO? They have received all their money... it's like when you buy shares in a company, they don't get any of your money beyond the IPO
Good comparison, but don't forget companies always keep a part of their shares/coins, which they can resell on the market. Many coins use this to budget new developments and marketing for example, meaning the more value their coin earned the less equity they need to use...