They have something else entirely NOW. I need to nail down what burden of proof exactly we're talking about because I don't want to waste my time if you are not even really open to the possibility that your belief is incorrect.
Don't waste your time. I will believe when the facts show that I was wrong.
The issue is whether or not the network effects are strong enough to prevent that scenario.
The survival of altcoins kind of answers that, doesn't it?
In fact we seem to be moving already away from a "bitcoin network" to a generic "cyptocoin network", whose members will devote their mining efforts to whatever cryptocoin their equipment can handle that provides the best return at that time. In that case the "network effect" will no longer be a
bitcoin advantage.
As I see it, right now the bitcoin price is sustained mainly by speculation
I don't entirely disagree, but why is this a problem?
If there is no external factor to sustain the price, speculation alone may take the price anywhere -- and will eventually take it to zero.
Common stock prices can be justified in terms of expected sales and profits, hence expected dividends and/or growth of assets. But there is no logical argument that justifies why the BTC price now should be 600$ instead of 6$ or 60,000$.
It is 600$ basically because speculators think that it may go up to 650$ sometime next week. But why would it do that? Well, because next week perhaps the speculators may think that it may go up to 700$ in the following week. Or perhaps they won't. And so on. The price now is basically holding itself up by its bootstraps...