Just to add on to camel's comment the big thing is that we don't know what anti-anxiety medicine he was taking. Benzodiazepine and anti-psychotic medicines are what you'd give to people with anxiety but even then it's not given so easily (at least in the western world, IDK about Korea).

Hypothetical Scenario 1 - He took paracetamol overdose only. Wouldn't land him in ICU unless super serious (aka acute liver failure). As camel mentioned TOP is known to be a heavy drinker so yes it is possible he has chronic liver damage which would increase his susceptibility. I doubt however that this was a case of isolated paracetamol overdose and if it was then it's more serious in the longer term than a benzodiazepine overdose.

Hypothetical Scenario 2 - Benzodiazepine overdose. Low dose benzo is what he was likely to be on ("LIKELY" as we don't know the facts). Benzos are really hard to overdose on and you need like 10-20 pills combined with alcohol/paracetamol/salicylates to cause effects so profound that you get respiratory depression and land in ICU. However if treated in time before brain damage has occured from lack of breathing, recovery is speedy and without lasting effects.

No matter what the drug he overdosed on, considering the situation surrounding this event, the fact that he is in ICU, and the fact that this was most likely benzo OD, camel's scenario 1 is the most likely scenario. Accidental overdose is possible but I highly doubt that this is the case.

If I was his doctor I would definitely inquire about the circumstances surrounding this and refer him to mental health. I say this is a case of suspected suicide unless proven otherwise.