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?
Whales having that amount not bitcoin doesn't make bitcoin centralized, because you and I when we have the capital can be whale's as well, bitcoin can be used to purchase many crypto-currency so bitcoin is not in any limited amount, so I don't think the whales have 50% control of Bitcoin so it's still a decentralized crypto-currency, but the believe whales have in bitcoin wouldn't make them sell off at the same time.