2. Big tech trends towards monopoly, BTC will eventually be controlled and one pool will control 51%. Dominant pools already have emerged, which means Monoply is inevitable. A truly decentralized system has no components that trend towards centralization.
I do not think complete decentralization is possible, where there is money involved, system will always favor the rich, and if there is no money involved, who will bother?
5. BTC has value only in it's "potential" - which creates real transient value because people want it - but that only runs until is potential declines. It's a fad. Like any pump and dump, the profit is in the sales.
You are right and you could argue same about every single thing in the world, i.e, a thing has value because people want it, otherwise it becomes valueless like dust. Even if Bitcoin is fad, it's going to last very long, it's offsprings are many, which will keep improving what Bitcoin has started as a technology.