MPEx may be a big fish, but bitcoin as a whole is a very small pond presently.
No argument there. At issue is the blind conviction of most everyone that Bitcoin has to be a sort of universal payment processor directly (possibly because all the payments these people ever engage in are to the tune of ten bucks).
In fact consumer level transactions, those five dollars for a moccachino, those nineteen dollars for a new pair of socks, those three hundred dollars for a new set of dildos and handcuffs constitute an area where Bitcoin's advantages are significantly dimmed (not reversible?! ouch), Bitcoin's disadvantages significantly magnified (wait up to six hours for a transaction to clear?! srsly!?), and currently existing infrastructure is well adapted (hey, Visa already does a billion transactions a week, why bother to put all the hard work into supplanting them? Why replace all the billion piece-of-shit point of sale units they already have on field? Guess what, they're not pieces of shit because corporations are evil, they're pieces of shit because when you do retail and interact with consumers you have to REALLY keep costs down).
Bitcoin's advantages shine at the other end of the spectrum. If I have to pay my Chinese suppliers for eight containers of socks or dildos or handcuffs or whatever else, I currently have to wait for a month or more just to obtain some bank's permission. The system of handling large payments is so complex, so risky, inefficient, and so downright insulting to the customer that I couldn't begin to tell you. That's where Bitcoin's advantages really matter, and as long as we gain market share there it makes absolutely zero difference if fifty or fifty million coffee shops start taking or stop taking Bitcoin. It may be a fact that mostly nobody currently involved with Bitcoin has ever paid for anything outside of retail channels. That happenstance doesn't make retail the only thing that exists.
I know that most everyone would like Bitcoin to be a currency for the masses, because most everyone actually is the masses. This still has no bearing, much like the case of the duckling that sat on a dragon egg. You can't expect the dragon to be sitting around the pond playing with your duckling friends, now can you? It's a dragon, it has dragony shit to do!
Store of value? Great, sure, forever. Ultimate unit of account, gateway to real finance as opposed to the wrestling show put up by Wall Street? Sure. Payment processor? Sure, if you're buying a plane. If you're buying a cup of coffee enjoy it while it lasts, but don't expect it to last forever. It just makes no sense to buy your cup of coffee in Bitcoin (tho it may make sense to buy a Bitcoin's worth of store tokens once a month, and from there on the gate is wide open to Bitcoin-
based payments, using bitcoin-backed private currencies, such as United States Dollars, Unified Store Dingdongs or Universal Spurious Dobaloos. It's just that they won't be put through the blockchain, because there's no need to put them though the blockchain and no benefit to doing so.)