80% of bitcoin trade happens at Mtgox which is centralised.
How do you get 80%? Is there a well-defined set of bitcoin addresses that belong to MtGox so that we can compute the ratio of the value of transactions involving them to the value of all transactions?
I think you mean 80% of the bitcoin trade in currencies, perhaps even just the pound. The ability to convert between bitcoin and your local fiat currency is becoming less and less important. Sell silver, gold, copper, services, food, whatever you want for bitcoin. And sell bitcoin for all those other things. I doubt very much that MtGox has 80% of
that trade. Closer to 0, I imagine.
We, as the bitcoin community, have the opportunity to utterly destroy the idea of fiat currency. Fiat currency isn't something you can do without large amounts of coercion and deceit. The way we destroy it is by trusting math instead of authority. We are brainwashed into measuring value with fiat currencies, but value is subjective and underpins our cooperative human nature: You have something that is more valuable to me than something I have, and I have something more valuable to you than something you have. They are the same two things (whether time, stuff, trust, reputation, notoriety, or whatever), so we're both better off trading them. We need to unlock our lips from around the nipple of fiat currency and embrace the underlying fact that we all have different values and those differences make us valuable to each other
if we can trade. Bitcoin makes this possible through the Internet
because it's public and timestamped.