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?
I don't think that 40% in hands of 1000 people is a sign of centralisation. Moreover, everybody know that Bitcoin is the most decentralised one. But actually, whales on crypto market is a real problem as if we are talking about small market cap coins, they are really subjected to impact of whales that can pump or dump the price very easily and nobody can deter them.