I wonder if legal use of pain medication (which are often opiates) during his football career eventually played a role with him using cocaine, which is also an opiate, but perhaps can be easier to obtain than pain medication (having to get prescriptions, go to doctors, etc.) I see a lot of people addicted to pain medication, and it is extremely difficult for them to kick, both physically and also mentally. They fight severe depression at the same time they are trying to overcome the withdrawals, but the depression continues for a long time afterward.

It's hard to say what the root cause is, because it is likely a combination of a lot of things, but the abrupt end to being a revered sports figure to being an average joe is difficult for a lot of athletes, as you said.