oneday people will realize that gold is only another metal, and millions of tones of it are already stored away for no good use
It's used as a de facto hedge against currency risk, if I understand correctly. This is not 'utility value' in the traditional sense, but loosely speaking is a kind of utility in and of itself, just a slightly arbitrary one. I mean, it doesn't mean everyone can just throw that gold away. It's a little bit like insurance, I suppose (if you plan to hold on to it).
In practice I can't see how the gold in vaults could ever be distributed equitably should some economic apocalyptic catastrophe result in a reversion to gold as currency, but then I don't really know much about these things.
opec is also holding back a whole lot, they could push the oil price alot lower if they wish, I don't think they could or would remove more crude.
They could push it lower indeed, or higher; pity we have price fixing. The higher they push the price, the bigger the pressure to come up with alternatives. Let's hope something else e.g. solar becomes cheap within the next couple of decades (and that we get some breakthroughs in battery tech). These ARE the future - so whoever comes up with something clever here will get very rich. Looking at the state of the tech, I think that we will have some interesting breakthroughs within the next decade or two, which may be why Opec is holding the price high now - i.e. make money before alternate energy sources cause the value of oil to drop.
I may be wrong, but i'll rather invest in something that is more ground breaking, and will always be a better need to humans, and thus may always be profitable.
Yes, for all intents and purposes gold "investment" is only a speculative investment, not a true investment, especially if "invested in" via instruments. But even if you put a gold bar on your kitchen table and stare at it, it isn't going to do anything to create value for you.