I wouldn't say meth is popular as much as it's so addictive you go from a recreational user to addict within a handful of uses, if even that. The high is intense and gives you lots of energy, but dissipates quickly and coming off that rush of endorphines creates a vicious cycle of continuing to use to not crash. Long-term meth users can actually deplete their central nervous system's ability to produce endorphines due to constant overproduction and basically lose their ability to feel pleasure. The damage it does to your body is very quick - there's significant weight loss, damage to teeth and tooth loss, and can cause compulsive behaviors like skin picking and hallucinations. The "fun" effects of meth are quickly eclipsed by how physically and neurologically damaging it is. Its prevalence in rural communities, at least in my experience, was attributed to helping people who work long or over night shifts stay alert. It also was at one point fairly easy to make at home - a store where I went to college was shut down because it had a very popular section that just so happened to have all the chemicals and equipment needed for a home meth operation together.
Heroin is similar in that it's also highly addictive and quickly causes physical and neurological damage, but the high is different - euphoric, often causes passing out and an overdose is more likely to be fatal since it's an opiate and can stop respiratory function . The withdrawal from heroin is brutal and makes users feel extremely ill which fuels a cycle of getting high again to avoid those effects. Most people using heroin now are turning to it once they can no longer afford Rx opiates or want to use something more potent and more affordable. I've never heard of anyone using meth because they couldn't get pain killers - this is a completely different class of drugs as meth is a stimulant and heroin is a depressant. Heroin these days is rarely even just heroin now, but cut with even more powerful opiates like fentanyl which makes overdose even more likely. Emergency treatments for opiate overdose like Narcan are also less effective on fentanyl. Again, not a substance you can really be a recreational user of like marijuana or ecstasy, the damage/dependency effects are much stronger.
BG doesn't look like typical heroin or meth users - they tend to lose a lot of weight very quickly into using. If I had to guess a substance he'd be using, I'd go with old fashioned alcohol. BG's nose is the only feature we have some definition of and I thought it's possible he has rhinophyma due to how round and wide his nose is.
