Detail I was unaware of. Looking at these folks, forgive me, I don't doubt time and circumstance is relative. I would put forth it isn't heartless. Clueless, numb, scared, etc. I doubt they were careless or unconcerned. I bet self concern was one of the selfish ideas worried about.

Inaction isn't carelessness for addicts. They've overwhelmed by minutiae, often. This was immediate need to ignore. This couldn't be ignored. It's fucked up.

This was someone 'close' to them. They're fucked up on drugs. Barely living themselves. A dead body isn't ignored because they enjoy it or don't care. You might forget or disregard takeout in the fridge for an extra day because you're not hungry or busy. For them, this was likely similar. Drugs are bad