Some say that cryptocurrency prices can be manipulated by wealthy individuals. Despite being decentralized, it seems that price movements can be controlled by specific entities.
It depends on which crypto asset you are talking about. Altcoins are not decentralized but bitcoin is. It is still decentralized so no one can manipulate the market. Let's say a whale owns 51% of the total Bitcoin supply. Then he can manipulate the market. But it is not possible for one person to own that much. Even if you add all the whales available in the Bitcoin market, they won't come together because different people have different agendas. So not quite possible for the moment. But no one knows what the future holds.
So, in your opinion, can everything related to money in this world be manipulated?
To some extent, yes! It can be manipulated if it is related to money. Market manipulation is done by individuals or organizations that hold the power and money to do so.
What kind of people are capable of market manipulation?
People with huge capital and people who have the power. Like billionaires and Governments. Governments control the value of money and could change it at any point. This is power. And people with huge capital could invest in something and then manipulate the market at their will. That's huge capital. Money gives you power and power gives you money. It's a cycle and those who are in it are capable of manipulating the market.