We need diversity so that no coin will have an ultimate monopoly. These new coin are an improvement over the older coins. The world is a dynamic place and so this changes all the time
You absolutely right here, the coming of new coin /token has a great impact on the existing coin/token in the market. These new start up bring in stronger competition amoung the various coins in the market especially if most of these project comes with a purposeful economic need of the people. For example, while one major intention of bitcoin was providing anonymous transactions, the digital currency’s technology has been ineffective at doing so. Bitcoin transactions are pseudonymous, meaning they take place between bitcoin addresses that are randomly generated strings of letters and numbers.
However, one altcoin that has provided far greater privacy is monero, which has become the dominant cryptocurrency of the Dark Net.
Another example of a currency that provides superior privacy to bitcoin is zcash, which leverages complicated mathematical formulas called zero-knowledge proofs to confirm senders and recipients without revealing their identity. Etc