A lot of us are aware of the ideology Bitcoin maximalism. To put it short, a bitcoin maximalist believes that bitcoin is the one and only crypto needed. A bitcoin maximalist believes that bitcoin will be the only crypto to give you significant profit and the one that is the most useful in the real world.
So far, Bitcoin is the only needed cryptocurrency among all. If you pay attention you will see every other cryptos were copied from Bitcoin for speculative purposes, without adding any practical usages or principles behind the altcoins. Ethereum can be considered a major success, but that is mainly due to the speculative usage, anyway, since many other developers use its blockchain to launch their own tokens.
However, there aren't any guarantees it will remain like this forever. It's not a static world, rather it's a world in constant changes in every areas, so it's not different with cryptocurrencies. Maybe at some point a superior currency to Bitcoin will be created, and once it happens, Bitcoin can indeed become obsolet.
Therefore, to be a Bitcoin maximalist means to deny that possibility to be real, what I consider to be denial of reality.