And satoshi don't like to crash bitcoin economy due to his greed.
There are many different logical possibilities, but the most obvious ones are these, to me:
A) Satoshi is a person
- he's dead and his heirs didn't know who he was
- he believes in bitcoin taking over the world's economy ; then it would be silly to sell his coins for a billion, when he can get a trillion and be "master of the world"
- he would have liked to sell them, but he doesn't know how to do so without giving up his anonymity: for sure, the exchange on which he sells the coins will know who he is, or to what bank account he withdraws. He was already pretty paranoid in the old days.
- he didn't bother to keep the private keys ( <-- cannot believe this)
- he never had the keys himself, because he was working for someone.
B) this last point brings us to: Satoshi is an organisation. In fact, the points are similar
- the association doesn't exist any more (for instance, the keys were in escrow, and the different signees don't agree to get together any more/are dead/are in prison /....)
- they are waiting for bitcoin to take over the world economy at which point they own a big part of it and will be the rulers of the world
- they don't know how to cash out without getting caught/found out
- on purpose, they didn't keep the keys, because they wanted to establish a system that would modify the economy/finance
- they were a group, doing this in command of a higher entity (a state, a rich family, a terrorist organisation, ...)
I would rule out B) in it's entirety. It's simply impossible that an organization remains coordinated enough that after 8 years there isn't a single leak of who or what satoshi was, and none of the members of the organization have moved a single coin.
My take is that A) satoshi was a single entity, and this entity either died or somehow lost his coins. Even if he believed in his creating 100% and knew BTC was going to be worth $1,000,000 each in 10 years, he would be too tempted to cash out some of them just in case. So unless he was already a multimillionaire and didn't care, it doesn't make much sense.
So either dead, or lost keys for me.
I wasn't giving my personal opinion, but rather all the logically not totally implausible possibilities, from which we can then try to eliminate branches that are too much in disagreement with what is factually known. I'm not entirely excluding "organization" however, because this may indeed be an explanation why the coins never moved: no single entity HAS the keys. I agree with you that it cannot be a LARGE entity. But 5 people or so, why not ? 5 people that are sworn together to become the rulers of the world and have the means to kill one another if ever someone fails ? After all, how big is something like the Equation group ? (I'm not suggesting they are the same, but of similar constitution).
That said, there is indeed no need for this to be a group: the work and the quality of the work are perfectly "deliverable" by a single relatively smart and competent person after all.
I'm also not entirely convinced of the idea that they will never move. After all, you don't do all that work if you think it is shit, and will go nowhere. You don't break your head to have cryptographic protection for centuries, if you think it will be forgotten 10 years from now. As this stuff is perfectly designed to be a speculative asset with a price that "goes moon", and you think that this thing will take 20-30 years to go mainstream, why on earth would you expose yourself to being tracked earlier, if you can be the master of the world 10-20 years later ? If you bet a coin will be of the order of a few million $ of today's worth, why on earth would you cash out on a measly exchange when it is thousand times below its value, and you expose your identity when it is not yet powerful enough to keep it safe at that moment.
I do not exclude that bitcoin is one of the biggest financial hold-ups in history, or at least, an attempt to it. In fact, the potential to financial hold up is larger than anything that has ever been achieved by armies and politics: no single person has ever held 5% or more of the total financial system. If the delusional dream of bitcoin comes true, namely, replacing the financial system, we have an entity that has more than 5% of the total system in hands and is entirely unknown. Personally, I don't believe in it overtaking the financial system, but that was clearly not the PoV of the creator of the system. So it looks to me like a perfectly logical explanation of why none of these coins have moved: they are waiting to rule the world.
It is this last potential aspect that makes me think rather of a group. Why would an individual be interested in "ruling the world 20-30 years from now" ? You can be dead. You will be old (unless you are very young when you made it). What's the point ? However, an organisation with some "destiny", that's something else. This is why I don't exclude the possibility of it being a group, even though the communications by Satoshi really sound like if he was just a dude in his basement.