There's orders of magnitude greater usage for Bitcoin. BTC transfers are worth thousands of times more than STEEM transfers every single day. Not to mention, Ethereum and its many ERC tokens have a far greater diversity of operations and transactions than Steem, as do other several other chains, almost all of which have zero lock-in. Or, EOS, which processes dozens of times the number of transactions as Steem, and has a (still unpopular) 3 day lock-in.