For me, hiking with a group is more hazardous. That's because I am slow (and getting slower with age), and attempting to keep up with a faster group inevitably leads to falls. When alone, I hike at my own pace, take plenty of time over rough spots, and don't attempt anything beyond my current ability just because a group wants to do it--a situation I have frequently encountered on group trips.
I've also read a number of accounts in which groups got into big trouble despite supposedly experienced leaders. One prime example some years ago was a meet-up group advertised as an introduction to winter camping. The leader ignored the weather forecast (TV reporters were touting the coming weekend weather as the "winter storm of the century," which meant that it at least was not a mild storm). No effort was made to ensure that the participants had the proper gear--in fact, participants were told not to bring snowshoes, and they were not told how to keep their gear dry. They also camped in an unprotected location with poor drainage. Nobody died, but some toes were lost due to frostbite and the entire group (including leader) had to be rescued because the snow was too deep for them to walk out.
I would say that hiking alone is (assuming the leaders are far more competent than in the above example) more hazardous for inexperienced hikers. Those of us with many years' experience in varied environments (75 in my case) are probably better off solo.
I personally think the drive home after the trip is the most hazardous--the driver is tired, it's getting dark, and the road is filled with equally tired (and often inebriated) drivers trying to get home as fast as they can!
Although you will profit from your vast experience, every year your age will increase your medical risks, like cardiac, stroke or breaking a limb, etc.
One could keep radio contact or telephone reach while hiking. And you could try to find like minded people in your region via the internet to hike. There may be more people that prefer a slower speed.
Hiking guides and survival instructors, who risk the lives of their trustful students, should be prosecuted and punished by the government.