The inherent value of any currency is based on these 5 factors.

1 scarcity - limit on supply, difficult to counterfeit

2 fungible - all coins are the same

3 divisibility - 1 / 100 millionth of a bitcoin is smallest unit. crypto is high divisible, an important feature if there is deflation.

4 durability - dollar bills get old and torn up. whereas, computers and drives crash and you can lose your private key.

5 transferability - cash and gold require physical transfer. banking: ACH, credit cards, wire transfers have fees. bitcoin: global internet transferability. transaction time should be less than 10 minutes. fees were low initially but have been going up due to network congestion.

However they main thing that makes a currency valuable is willingness to exchange it for goods and services. That is the useful part about the bitcoin "bubble." It serves to increase adoption of it's usage.

edit: formatting and note about losing keys mention in comment below

Regarding durability, because of cryptocurrency's distributed nature, a better parallel would be lost private keys and transactions that destroy coins rather than drive crashes.

the USD, public perception and its subsequent psychology, and mining. or did i read the question wrong.

The USD is backing bitcoin? How so?