I converted some of my Steem and SBD to Bitcoin on an exchange (Poloniex). I sent the funds from here to the exchange and then just bought a micro amount of Bitcoin with my Steem & SBD. There are lots of exchanges to choose from. I just bailed from Poloniex because they're having too many issues. I'm using Tradeqwik from now on, I think, for a whole host of unrelated reasons.
In a nutshell... you, too, can own some Bitcoin. ;~D