imagine if a billionaire buys bitcoin using any exchange? Imagine if someone who has many bitcoins decides to sell everything at once in an exchange?
I think your points nail it exactly, and this is the reason why penny stocks are so much more volatile than, say, Microsoft stock. I think a big component of volatility is market cap. Another big one is the amount of speculators and how much money they're putting in and taking out of the market.
Bitcoin's market cap
is relatively small, and I think that's why we're not seeing hedge funds and other Wall Street-type investment institutions buying it. They can't really buy or sell large amounts without moving the market--or getting stuck when there's little liquidity. Plus bitcoin is a new thing, only 10 years old at this point.
Anyway, I don't expect bitcoin's volatility to flatten out anytime soon. We might get periods of stagnation, like when the price was pinned at $3500 or $500, but when it moves it's pretty dramatic. And IMO that's part of the appeal of bitcoin and I'm sure traders wouldn't want it any other way. They make a lot of money when the price swings up or down.