I'm hesitant to agree with this statement outright -- on the population level, I do think it makes sense to pursue interventions that increase life expectancy. But on the individual level we must ask, are we comparing apples-to-apples years of life? For example, I would pick 10 years of life with vitality over 12 years with mobility issues.
For ADHD medication specifically, for most people diagnosed with ADHD I would expect to see both improved life quality AND life expectancy. Of course, specific individuals may experience worsened life quality on medication, in which case they will have to weigh up whether they want potentially longer life with lower life quality.
Given the kinds of mortality causes from ADHD, I would think the calculus looks more like "ADHD meds make me feel yuck but maybe that's worth it to not get fired regularly, because my family needs me to support them financially and being fired regularly makes me depressed and suicidal".