So, after a rough patch involving medication in October, I'm back to working on the background for that novel idea I mentioned.
I've got a timeline about what the initial disaster will be like when magic first comes back, but now I'm trying to imagine the steady state once people get used to the idea. The way I have it set up currently is that the average optimal age to attempt to gain magic is about age 50 for men and 55 for women. Remember, the idea is that if you undergo the ritual to gain magic and you are young and fit, you have a 50% chance of dying in agony and a 50% chance of succeeding in agony. Your chance of success worsens as you get older and sicker, until it falls to essentially zero at age 85.
The ages of 50 and 55 are derived by me staring at mortality rates. They're roughly the ages that mortality rates start to get noticeably worse.
Also remember that one of the biggest prizes of gaining magic is that you can use it to maintain and regain youth. A magician (mage, magus, wizard) who doesn't do something stupid to off himself can live for a very long time.
So, this knowledge has been around long enough that it has entered popular lore. Rational people who want to become magicians can plan their lives around these facts. They get married young and have their children young so that the kids are all finished being reared by the time the would-be magicians are fiftyish.
On the one side is a chance at a greatly extended healthy life with the ability to be a wizard. At age fifty the chance is about fifty percent, but the true long-term chance is closer to twenty-five percent. It's also part of received lore that about half of new magicians do something to kill themselves or cause others to kill them within a short time of gaining magic. Of course, because of the Dunning–Kruger effect, everyone assumes they aren't going to be in the idiotic half.
On the other side is the rest of your life. If you are on the losing side of the bet, you don't get to watch your grandchildren grow up. You don't get to enjoy your retirement. You are dead, dead, dead.
I'm having trouble guesstimating what percentage of rational fifty-year-olds would take the gamble to gain magic. As an expected value equation, it's a slam dunk for magic, but years of life aren't anything like dollars and cents. Do you have any feel for what percent would take the gamble?