Thanks @yabapmatt! Indeed that was much of my argument, and I agree it could be a valid argument for Steem as well! It's certainly exciting to see a blockchain based app that seems to have vibrant, real world usage.
Beyond just users, Bitcoin has also had years of folks trying to break it, and it's security and incentive structure have been stressed more than any other. That it continues to operate well makes it more likely it will continue to operate well.