The doing nothing treatment leads to death 100% of the time since you don't do CPR on people with a beating heart.

Slightly worse than nothing; saves a tiny bit of exercise for someone. 7% of the time it saves a life.

For bystanders, the raw numbers from the article reflect a 7.6% survival rate became a 10% survival rate. An absolute improvement in about 24 out of 1000 cases, though for those that do 'survive' maybe a 33% increase?

Though those numbers strongly hint at over simplified variables. Is there other medical help available? (E.G. an AED, maybe combined with CPR?) Is EMS close? Are they near a medivac capable landing site and a level 1 trauma center? How does this change across patient demographics?

For my own health, this goes back to end of life management questions, can I recover or even improve to a degree if a procedure is done? As someone with hopefully decades and maybe even a chance at upload or archival if I live long enough CPR probably is worth it for the cases where survival is improved; but only if all the other options are exhausted first.