Re: when I was a System/370 operator in the 70s / 80s...
In my experience, this kept up through the mid-noughties at least. Before I worked in technology, I was in a physical profession, providing "relocation services" under corporate contract for their people. Moving furniture. Say what you will, I never had to worry about the job I had just concluded again past the end of the day. I'd still be doing it if the money was there and my body would take it. Technology was a lot more fun when it was a hobby.
Anyway, the company had contracts with Sun Microsystems, Yahoo, Google, etc, and packing up the belongings of their employees, I got to see a side of them that I doubt their colleagues ever did. Meth use in particular was a persistent theme. Especially at Sun Micro around the time that Oracle devoured them. I can empathize with the decision to get high, under the circumstances. Sun was an awesome company, and from what I heard, the best place to work in the Valley at the time. Being made redundant and watching everything you'd built get chewed up and masticated into paste by Big Red must've hurt.