To be honest, it depends on how responsible a student is. I myself is a still a student who relies in Bitcoin to help me finance myself but I for once haven't forgot about my studies and had an average grade of B+. You should consult your students and approach them to give them some advice. It's not Bitcoin's fault but it was students entirely. 
I agree, sometimes you need to look in a different angle to saw what is the true problem. I think the problem is the student, being irresponsible and lack of discipline. I am also a college student and I am not affected by the bitcoin.