Not arguing your main point at all, but I wanted to correct your last statement. While not considered safe, cigarettes have proven to be remarkably protective against the development of Parkinson's disease in a slew of studies spanning decades of research. This is relatively little-known outside of the field. I did my PhD in Parkinson's drug discovery, and it was one of those findings that is frustrating due to the lack of other effective therapies for PD prevention and the obvious deleterious effects of smoking on heart disease, lung cancer, etc. Here's a relatively recent review paper on the topic: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5494127/.

Relevant excerpt: "Population-based studies have shown that smoking was associated with approximately 40–50% reduced risk of developing PD. [10, 11] This inverse relationship between smoking and PD was dose-dependent: age-adjusted relative risks (RRs) of PD were 0.8, 0.6, 0.5, and 0.4, for 1-9, 10-24, 25-44, and 45+ pack-years, relative to never-smokers, as shown in a large prospective cohort study [9]. There is also a temporal relationship between cigarette smoking and PD risk [9, 17]. Individuals with more years of smoking, older age at quitting smoking, and fewer years since quitting smoking had lower PD risk. Researchers prospectively observed a significantly lower risk of PD for smoking as early as 15 to 24 years before symptom onset, but not for smoking 25+ years before onset (n = 143,325) [17]."