~Avoiding a centralized authority controlling the system is one of the issues that Bitcoin seeks to overcome. If there is a large demand and widespread adoption, a supply shock would then occur.
It is impossible for BTC to overcome centralized authority since the market is open and free for everyone to buy as much btc as they can afford.
The problem with adoption is not just because the whales or centralized authorities have access to a large amount of btc to manipulate the market but also because the majority of investors (whether small or big) see btc as a speculative asset than an alternative currency. So what needs to change is peoples perception.