In any force, not every descendant had a protector. Only the most promising prodigies with outstanding talent who could beat their peers could have a protector to protect them.
For protectors, it was not only to protect the hope of their family's rise, but it was also closely related to themselves. Such top-notch experts would lower their status and do nothing but protect a prodigy for decades until that person rose to become a top-notch expert themselves.
The benefits the protectors would obtain were naturally self-evident. Just the gratitude of these prodigies who had risen to become top experts brought countless rewards, bringing huge gains to the protector and their descendants.