Everything is a risk, at least in terms of probabilities. Is it a reasonable risk is a more interesting and open-ended consideration. A solo day-hike is a reasonable risk in my estimation, but not when you add the issue of inclement weather. In the US Rocky Mountains prudent hiking culture urges hikers to descend below tree-line by "afternoon" as inclement weather is likely to occur after then in the day and trees can provide some protection.

Descending far below rated depths in a carbon-fiber single-hulled "submarine" operated by a lunatic seems to the average person to be a simple reckoning of supreme foolishness or gullibility on the parts of the victims of the Titan implosion.