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?
First you need to be clear that bitcoin is not centralized. Bitcoin is only crypto currency which is decentralized in true sense. Also it does not matter if 40% of the bitcoins are owned by 1000 individuals. They won't dump them together and even if few of them did, there are too many people who will be willing to buy cheap and hence don't expect the price of bitcoin to fall too much.
if the price of bitcoin will continue to soar, it seems certain, especially now that few people understand bitcoin around the world. the 40% control is not a worry if they keep it, and that means helping the price increase. but here there are different human natures, and have different needs, so their actions towards the btc they have will not be the same