Decentralized can have many meanings. What is important is that you can transact with anyone without a third party having any say. For that 99% of all coins could be in the hands of a single person as long as there would be enough left for others to use.
> Add this to the obvious fact that the vast majority of new bitcoins mined are from china, which due to the scale of processing power now has a monopoly due to capital barriers
As long as they do not collude to destroy or disrupt the network it has no relevance at all.
> This has become nothing more than a pyramid scheme that adds no value whatsoever to the world. Not cryptocurrency as an idea, but bitcoin's current iteration and implementation.
As Bitcoin is practically useless due to high fees and congestion, I agree. But not because the reasons you gave.