I have often thought that personality was the most critical component of a solo diver and not time in the water so
I see this as true more and more. Eventually I won't even feel the need to discuss it any more.
People that solo in bad viz, I can in no way relate to. You just don't know what is there. It is a crap shoot. Diving solo in gin, I am very sure I can keep myself from being entangled, just like if the light is on for my trip to the bathroom.
It seems so simple to me. Solo at 70 ft or less, clear water, nice conditions. Not much can happen that I cannot get out of, as long as I have used my brain before getting in. I am a pretty big chicken and I cannot see one thing happening. All these other fancy scenarios just don't enter the picture for a prudent solo diver. Anybody who solos in really bad viz---shouldn't be a solo diver. A good solo diver personality figures this out easily. Sometimes I think people who over intellectualize things operate at a disadvantage in some cases.
To the original question, I find my reasons NOT, have not changed.
1) poor shape, sickness like flu,etc
2) family pressures not to
3) bad viz/ entanglement risk
4) ocean conditions not favorable...current, etc
redundant air, formal coursework, don't really effect me as far as I can see.
My best prevention is to stay in good cardiovascular health, by a huge factor.
Aerobic exercise barely gets a nod in these debates and yet...
look at the numbers and decide if a pony or a workout is more likely to keep you from dying down there.