Yes,bitcoin has been manipulated by some people called whale but their manipulation rate can be diluted when more number of people adopted to the bitcoin system at the time the funds will be dispersed everywhere so whales may not have enough funds to dump or bump the prices.But we can't say the manipulation happening always because when we see the price chart there is some look like movements in between years so this means this called as natural price movements too.
Dilution won't happen if the whales dump and then pump as they are just regaining their coins and also making a profit out of those dumps. It is actually the exact opposite happening, where newbies in trading are losing their coins in panic sells, and the smart ones are just hodling and accumulating.
An somewhat even distribution will not happen in decades or maybe never.
There will always be whales, and unfortunately for those desiring some fresh blubber
, it's impossible to get rid of them. BTC is the ultimate store of value after all, isn't it?