Whales, big miners, or those who hold huge amounts of bitcoin, if bitcoin becomes mainstream, won't big holders be like ultra rich people in today's world? Some holding lots of money, whereas some very less?
Sure, but that's true of almost anything. People who successfully predict the future can leverage that into money. But they also incur the risk that they will guess wrong and lose money.
If, instead, bitcoin collapses, miners will find themselves with very expensive space heaters. And big holders will find that they have nothing at all.
Bitcoin is far from a sure thing. It could start a slow, steady slide down to $0 tomorrow. Or it could double in price next week.