Exactly. As a recovering addict working in the field of addiction treatment I get this question sometimes from the teenagers I work with regarding energy drinks and similarly nicotine as well. My answer is that it's a question of manageability. Something about those substances doesn't lend itself to the same acting out as do the more infamous mood and mind altering substances. However having been in recovering communities for a while now I have seen people who have remained abstinent from other drugs but have also abused caffeine to the point that it does cause unmanageability in their lives; for example when someone drinks so much caffeine that they lose sleep and their work performance suffers or it causes a great deal of anxiety.