40% of all Bitcoins are owned by just 1000 individuals.
This gives them a disproportionate amount of control over the market as they are able to dump them at anytime.
This is not to mention the high proportion of bitcoins held by miners and exchanges, who may have perverse incentives to ensure that as many people buy up bitcoin as possible and hold it for long enough for the price to rise.
Is there any way to deal with the high degree of centralisation that Bitcoin has?
It gives them the advantage for sure, but without manipulating the mainstream media they will not be able to do much, People will start to notice their pattern because most of the people do the same thing again and this world lack intuitive people so they will need people to do mass manipulation into market, Pump and dump schemes , FOMOs , etc.