Because they're looking for some reality-based reason for its value, so as to judge whether it's currently over or under-valued and can rate, like with stocks listed on the NYSE, whether it's time to buy, hold, or sell. There are exceptions in the market eg Tesla, with it's P/E of ~200, or GME and the WSB nonsense, but most other stocks have a P/E ratio based on fundamentals. Fundamentals that bitcoin utilitarians are looking for in cryptocurrency and are coming up short.