But, I have seen many project with zero pre-mine and following all other decentralized rules got failed as well. In my understanding, being decentralized got nothing to do with your investment.
There are a lot fake decentralized and less decentralized project, that's make the coin is useless and not successful, also they're not open source and not giving a way to verify their protocol. Monero is the best altcoin until now, it's another project which is has a purpose for privacy and decentralized. As you can see there are a lot privacy coins comes up, but they're offer less privacy unlike Monero.
A project with a decentralized protocol is truly not controlled by others. You have complete autonomy, but the project party does not know where to go, and the tokens of this agreement are meaningless. There is no value left. It is the most reliable if you want Satoshi Nakamoto to create Bitcoin. There is only one reason, everyone's consensus is indestructible.
It means, there's no need to create new coins if Bitcoin is still become the best crypto in terms of decentralization. I don't see any reason why people keep creating new coins except the sole purpose is to make money.