I'm going to come at Nemrod's idea about different personalities in diving from a different angle.
Arguments over whether 'standard' buddy diving vs. properly trained & responsible solo diving is statistically safer, given that either is relatively low risk, miss the point.
Scuba diving has some inherent risk no matter how well and responsibly it is done, yet at the recreational level diving is unnecessary. So the very fact I choose to dive testifies to the fact I'm willing to take on some risk to do something I want to do.
Likewise, as long as solo diving is safe enough, I don't really care that buddy diving might be safer. Let's say my odds of death or serious injury on a dive I want to do solo are 1 in 100,000, and taking a buddy would drive that down to 1 in 300,000, using wild guess numbers to make a point. That's not going to change how I dive.
I think I dive responsibly and safely enough. Not the most anally and lowest risk possible.
How about an example. I've enjoyed in a number of threads TS&M discussing the GUE DIR system, her dedication to pre-dive gear checks for self & buddy, well-trained fine buddies she dives with in her region, the 'non-aquarium' conditions of Puget Sound, and the dedication and commitment to the sport she brings to her dives and dedication to planning and 'diving the plan' her buddy teams may display. I have no doubt she dives safer in more adverse conditions and that her diving approach is by any objective 3rd party observer 'better' than mine, and she obviously enjoys her diving.
Yet I'm not signed up for GUE Fundamentals or likely to embrace DIR diving. I enjoy buddy diving with a good friend of mine, but I also enjoy solo diving. I have no intention of cold water diving in Puget Sound any time soon, if ever (might be tempted to do guided diving there if I were in the area). This is not because I think my way is safer, more philosophically sound, more skillful or better informed, none of that.
It's because I'm me. An adult only child eccentric introvert who grew up somewhat isolated and learned to appreciate solitude. Not a team sports type. Not a 'people person.'
Many solo divers will choose solo for reasons much different from mine. My point in all this is that the decision to go solo is often not down to whether buddy diving or solo diving is safer. As long as both are safe enough.
Richard.