I'm a septuagenarian diver well aware of the risks but also convinced that the risks are usually exaggerated. Scuba diving is usually a low energy, placid, calm, untaxing activity. That some people fall victim to the usual submerged coronary is, I think, often a result of their lack of experience causing them to become overexcited. In this respect it's much like sex. An older guy who has sex regularly is much less likely to experience difficulties, just like an experienced diver for whom frequent easy dives are no big deal.
I think a great many of the older divers who die are inexperienced and consequently hyper-excited, taxing their vulnerable heart and circulatory systems. I stopped doing very deep dives, dives in cold water, or dives involving strong currents almost a decade ago. The easy dives I do these days are about as taxing as a long walk or an afternoon roll in the hay, and about as likely to to kill me. Something will in the future, but scuba is no riskier than most things and a good deal less dangerous than, say, riding a bicycle uphill in bad weather.