Bitcoin’s value is given by the merchant who is willing to exchange it for something of economic value to you (goods, services, etc). These persons who are willing to trade with you for Bitcoin are considered the "economic majority", as they decide which Cryptocurrency definition they are willing to trade value for. The economic majority is the group of persons backing Bitcoin or other accepted Cryptocurrencies.
The US dollar value in contrast is guaranteed by legal-tender laws: Dollars are always accepted for paying taxes, and that reflects a value that will always remain, even if the entire economy decides to stop accepting the US dollar. Dollars are NOT backed by gold.
What do you mean "backed by a government"? Can you give an example? – JBaczuk – 2018-11-29T14:32:34.543
Spelling note: "monetary", not "monitory". I edited for you. – Nate Eldredge – 2018-11-29T14:41:55.413
@JBaczuk I am trying to get the answer for the following example. Assume I have a bit coin and want to buy a product from a marchent. Why would he sell that product to me for a bit coin when he bought it from the supplier for dollars. – SeethaRaam Devulapalli – 2018-12-03T02:53:04.117