Because there are relatively few buyers and sellers in the market and the amounts of transactions are small, so one big mover can shift the price a lot.
According to some blockchain site[0] the average transaction volume for BTC is something like $2.25m USD equivalent
For comparison, on an average day, SPY[1], which is just one security (albeit a popular one) trades something around $17,160m (e.g. $17.16b).
Because there's fundamental value behind most traditional securities, even if it's well below the current market price. If you hold a bond, it will (usually) pay interest and principal. Equities carry the value of the cash holding of the company, plus the potential for future dividends. These cash flows act as an anchor on the value of those securities (in both directions, up and down.)
> won't this problem go away as BTC gets more popular?
Maybe. It would have to get a lot more popular, and a lot more legitimate and regulated. At that point, it's lost all the cyberpunk appeal, and it's just another speculative asset.
According to some blockchain site[0] the average transaction volume for BTC is something like $2.25m USD equivalent
For comparison, on an average day, SPY[1], which is just one security (albeit a popular one) trades something around $17,160m (e.g. $17.16b).
[0] https://blockchain.info/charts/estimated-transaction-volume-...
[1] https://finance.yahoo.com/quote/SPY