Aside from price, it's a (very rough) measure of the number of people who would be willing to accept Bitcoin as a form of payment. The 'utility' of Bitcoin is

Aside from price, it's a (very rough) measure of the number of people who would be willing to accept Bitcoin as a form of payment. The 'utility' of Bitcoin is you can pay for things with it, so the number of people who will let you pay for things with it is a reasonable-but-somewhat-lacking way to value the 'fundamentals.'