Gold's current value is not related to its function as a material for jewelry, but from a myth that it is a store of value. If people would stop believing the myth, the cost of gold would plummet and stabilize around the value it provides as a material for jewelry.

Similarly, "art is lovely" is a really stretched argument. If you want, you could print your transaction block hash and consider it pretty as a math-art concept.

So yes, bitcoin needs people to believe in its value to remain valuable, much like everything else that is not a raw utility - nations, religions, money, corporations, gold, baseball cards, and so on.

Heck, even Ferraris would become much cheaper if people only valued them for their function. They cost a lot primarily because we value them highly due to myths and scarcity.