Behind every addict there's usually an enabler in some form. Sometimes there's a nasty feedback loop. Of course that doesn't negate human agency or its importance, however it makes for a convenient excuse. Agency seems unevenly distributed, but it also seems to vary within a single individual depending on what sorts of things they face and what excuses they have to avoid exercising it. Humans have a wide range of adaptations. In the modern world where even the very poor can live better than the wealthiest in olden times, exercising much agency isn't that important.