Rarity of Willers
Several reasons why strong faith (enough to become willers), while so desirable and powerful, rarely manifests in individuals:
Similarity of Faith Level: All people’s sentience originates from the faith of others, in the quality of the newborn’s sentience - and so generally fall within a band of “expected”, if not normal, behavior. They believe the baby has similar faith as the people they already know, and imprint their own psychological tendencies on the new sentience. As generally very few people have strong faiths to be willers, each successive generation also has very few among them with strong faiths to be willers. This also means however, that communities with few or no people of strong faith, will have fewer children of strong faith, while those brought up in communities strong in their faith will be more likely to be strong in their faith. This is not a genetic trait, but an environmental one.
Helplessness of Youth: Peoples see babies as helpness and needing protection. This faith effectively overrides the babies’ faith, rendering their faith impotent; and then when the babies try to will something, they won’t be successful. Generally babies don’t carry their memories of such failure in their youth, but generally parents will only gradually stop seeing the children as helpless, and only once they’ve reached an age when they’re seen as able to at least somewhat fend for themselves - post toddler age. But by then their long-lasting memories will have started to form, and the memories at that time are likely to still be failures. Also, even while they are toddlers they will have memories of their failures from when they were younger toddlers; and their failure is propagated through time, from when they were a baby into their adulthood. And so it is that parents’ very drive to protect their young, cripples their faith ability. This gives orphans and wildlings - who have people tending to them less - an advantage with faith.
Faith Weakening from Conflict: People can’t all be capable of using faith alone to alter reality, because if they could, they’d use faith to shape things in a way that other people don’t want, and they’ll oppose with their own faith. And in such a conflict only one or the other would succeed, and the loser would lose faith in their power. So the number of people who can alter reality by will alone, even if it were everyone at birth, is reduced to a tiny percentage of people, sufficiently uncommon that they will rarely run into one another and cause this kind of conflict - generally, one in several 1,000’s. A person generally really interacts with only a few hundred people in their lifetimes, and may meet a few thousand. This is also the reason why youths, and the cloistered, have a better chance of having strong faith, and are likely to lose their power as they age.
Parenting: A certain kind of parenting is important to build up the initial self-esteem, confidence, and narcissism. The child must receive a solid foundation for good feelings about themselves; which means that the parents cannot be excessively critical or demanding, and yet give the child ample opportunity to prove himself to establish internal locus of control; and must convince the child that they’re superior to others. This kind of parenting can quickly become problematic and get out of hand if not done right, and it is likely to result in incorrigible children, not to mention very likely to fail nonetheless. The importance of parenting for spellwilling is not known to most, and so the necessary parenting is rarely done.
Gullibility Requirement: Having strong faith can be a problem, as it first requires gullibility: you have to be able to fool yourself to use faith to alter reality, but that makes you susceptible to being fooled by others, the way “religiously inclined” people are more susceptible to religion; and the faiths and rumors and memes that others spread often work to their advantage, which is to your detriment. People who are gullible have an obvious social disadvantage, and so often don’t make it through life to reproduce; and so relatively few people are that gullible. And the newborns along with them, per the similarity of faith levels.
Lack-of-Doubt Requirement: Strong faith also requires a certain degree of recklessness and unwillingness to ‘check and confirm’; it requires one to lack self-doubt. And that self-doubt is what allows people to avoid taking on risks and challenges they shouldn’t take. Of course, if one isn’t careful or aware of their own limitations they can quickly get into trouble, such as personal danger or conflict with persons of authority and others who can alter reality; which brings about a faith weakening from conflict. Personal danger and ostracism from the community also work to make it less likely such people will have children, and so relatively few people are so lacking in self-doubt.