> Bitcoin is volatile and transactions are slow.
The Bitcoin blockchain is slow (as all blockchain are, relatively speaking) but most Bitcoin transactions happen off-chain, for example at the many Bitcoin exchanges, where bitcoins are transferred between customers at thousands of transactions per second using a central clearer (the exchange).
By depositing bitcoins at an exchange, you exchange it for that exchange’s Bitcoin credit, which has no limit on transaction speed, and when you want out you redeem your credit into a Bitcoin transaction.
This page shows the USD price of the credit instruments of the various Bitcoin exchanges: https://bitcoincharts.com/markets/currency/USD.html — e.g. a Bitcoin on Bitstamp currently costs 2439.84 USD, whereas the price of GDAX (Coinbase) Bitcoin credit is currently a bit more expensive at 2456.44 USD.