I don't feel you're looking at this objectively and I also think you do your students a disservice by casting blanket dispersions on something that has the potential to offer them quite a bit of opportunity. You remind me of talking heads back in the 90s telling everyone to stay away from that dangerous internet because it would corrupt public morality.
Again, our computer science undergrad students surely have learned about bitcoin well before I did, and are smart and adult and capable of judging for themselves. Some may be busy creating their own altcoins or bitcoin-based businesses, scams or not. I can't do anything about them. (That "student" I just mentioned is actually ex-grad, from the Mathematics department, who did his PhD last year on an applied math topic.) What bother me are the attempts to sell bitcoins to people who know nothing of computing, much less of computer security.
People may have said "internet corrupts" in the 90s, but it was bullshit. (The people around me in the 1980s and 1990s certainly did not say that.) "Bitcoin-related investments are often scams or failures" is not bullshit, unfortunately.