I think it is important, that one point should also be mentioned:
It is not a shame to stop something that is not within someones skills.
Every good trainer (whatever the subject is) takes the guy aside who has other talents and and tells him in a modest way that he should better play tennis than becomming an NBA star, if he realizes that fact.
A bad trainer tells the untalented guy all the time, that he will make it, just to get the hours payed he is teaching him something he will never learn…
This does not mean, that someone should not stick to learning, but this means that someone has to realize also, that horse riding is not everybodys thing, and its more profitable to invest his time and money in other subjects.