There are many, many young men and women from frum homes who have serious addiction issues. It is often a package deal with emotional and mental health issues. I am not someone involved in this at all, and know more than one person who died of a drug overdose, and several more that are in and out of rehab. Once an addict it's always there lurking.
When they are niftar there is a clear effort to keep it quiet, out of consideration for the families. (most of these are not reported on anywhere at all, very few are 'high profile'). I understand that fully, but the side effect is that people simply don't believe it's there.