1. Because not all altcoins end in failure, therefore there are still very many investors who want to make an investment because in investing we cannot predict 100% whether altcoin is making a profit or a loss.
2. we can't blame the developer because the success of an altcoin depends on the investor.
1. The vast majority of altcoins end equally - a complete failure. The vast majority of really good altcoins are on the verge of failure, at least in the eyes of investors who invested in them.
2. Success depends on many factors, and the primary ones are not investors, but team work and project development. As soon as the team stops working, the price of a coin falls off.