According to the American Heart Association [0], CPR can double or triple the chances of survival:
"Each year nationwide, more than 350,000 people suffer a cardiac arrest outside of a hospital; only about 10 percent survive.
When the heart stops beating, a lack of oxygenated blood can cause death within minutes. If CPR is performed immediately, it can keep blood flowing to the brain and other vital organs, doubling or tripling a person’s chance of survival."
Not to mention that AED's are more prevalent in public spaces these days. If you can provide CPR _and_ use the AED the chances of survival increase dramatically.
I think this proves the point -- Simon Kjaer was hailed a hero for 'life-saving' response to Christian Eriksen's collapse [0] and Eriksen was discharged from the hospital 6 days later (he had a defibrillator implanted). Had no-one done CPR he may well have died.
"Each year nationwide, more than 350,000 people suffer a cardiac arrest outside of a hospital; only about 10 percent survive.
When the heart stops beating, a lack of oxygenated blood can cause death within minutes. If CPR is performed immediately, it can keep blood flowing to the brain and other vital organs, doubling or tripling a person’s chance of survival."
[0] https://www.heart.org/en/news/2018/08/22/cpr-training-at-sch...