[vabmit]

I wouldn't say no one. There are a number of companies that trust Bitcoin enough to use it in trade for their goods and services. For example, ProtonMail (a secure private e-mail provider) trusts Bitcoin enough to accept it in trade for its services.

So, the same thing that gives the Euro and Gold value (that people will take it trade for goods and services) is one of the components accounting for Bitcoin's valuation. The majority of Bitcoin's value at this point is likely speculation. However some percentage of the value is not derived from currency arbitrage or speculation.

Even if Bitcoin trade participating merchants do not trust the market valuation of Bitcoin enough to be willing to hold Bitcoin for very long after they accept it as part of a transaction (and therefor immediately convert it to USDs) it is still valued by the participating merchant in line with the trade. The same could be said for the value of the electronic ledger recordings created by credit cards. They are generally viewed to have around equivalent value to USDs. But, they are not a currency either.