Also that extra 3-4 days (if a true statistic)is averaged across the whole population. In fact, it’s more like a bunch of people get no extra time and a handful get years because they aren’t dead from a heart attack (this is a good thing and how population based interventions work).
Even if it doesn't extend your life, it could prevent a heart attack that doesn't kill you but does damage your quality of life.
Same idea as people who say smoking or drinking just takes off the last worst years of life without acknowledging that your overall health will be worse. Really it's just making the worst years come faster