Korean health data from 410,489 smokers tracked over nine years demonstrates that quitting smoking increases Parkinson's disease risk by 60-61% compared to persistent smokers, with both recent and sustained quitters showing elevated subdistribution hazard ratios of 1.60 and 1.61 respectively. This competing risk analysis addresses a critical methodological gap in previous epidemiological studies that failed to account for the higher premature mortality among smokers potentially masking the true smoking-Parkinson's relationship. The findings strengthen the paradoxical inverse association between smoking and neurodegeneration, suggesting nicotine's neuroprotective mechanisms may genuinely shield dopaminergic neurons from the pathological processes underlying Parkinson's. This challenges conventional public health messaging by revealing an unexpected trade-off: while smoking cessation reduces cardiovascular and cancer mortality, it appears to unmask vulnerability to this specific neurodegenerative condition. The large sample size and sophisticated statistical modeling make this among the most methodologically robust examinations of smoking dynamics and Parkinson's risk to date. However, the observational design cannot establish causation, and the overwhelmingly male Korean cohort limits generalizability. For aging populations weighing health decisions, these results underscore the complex, sometimes contradictory effects of lifestyle interventions across different disease domains.