I agree with you that Bitcoin is an expensive ledger to maintain. That said, it's nonsense to say that low transaction costs (that's what efficiency means to the end user) is the sole factor for anyone besides Silkroad users and ideologists.
People pay a lot for security, and the problem with centralized systems is that they grant the organization running them both the means and incentives all the rents it can get away with, not only directly with added fees, but by using abusive tactics to pass the costs of fraud onto the user (see PayPal's infamous freezing policy) and by skimping security as much as it can.
Of course, you can reduce the likelihood of such events by adding external auditing, insurance, regulation, etc, but all of that adds friction which will inevitability result in increased transaction costs (TANSTAAFL).
If risk was irrelevant, nobody would invest in treasury bonds.
People pay a lot for security, and the problem with centralized systems is that they grant the organization running them both the means and incentives all the rents it can get away with, not only directly with added fees, but by using abusive tactics to pass the costs of fraud onto the user (see PayPal's infamous freezing policy) and by skimping security as much as it can.
Of course, you can reduce the likelihood of such events by adding external auditing, insurance, regulation, etc, but all of that adds friction which will inevitability result in increased transaction costs (TANSTAAFL).
If risk was irrelevant, nobody would invest in treasury bonds.