Fiat money is driven by the threat of punishment, as it relates to ones tax liability. That's why people want it - it's the only thing that the Government accepts for the payment of taxes.
If Bitcoins aren't accepted to extinguish ones tax liability, then their usefulness comes from them being a kind of scam.
That's why people wants it? Not sure... The majority does not want it, they are imposed to it, which is another manner, and something which you and I are unable to change, but for the sake of discussion, Tax was never an agreement between tax payers and governments, it was an imposition from the government to the people. Primarily (you probably aware about it) tax was a collection to provide public services to the tax payers which has been completely distorted over the centuries. Again the amount of Tax payers money that Central Banks received from governments (tax money) to pay interests shows clearly that Fiat system is The Scam system not Bitcoin. By the way , do you self vote your posts? lol