It's not really fair to suggest that instructor No.1 lacks brains because he wrongly predicted that Pianorak would never solo.
However, I have no sympathy for any instructor who belittles a student, or is visibly frustrated or impatient (at least, not repeatedly; we all have bad days now and again). It has happened to me, and there is no doubt that it is a very demoralizing experience that is (obviously!) counter-productive to the learning process.
To all instructors, my advice would be:
(1) BE PATIENT! Recognize that things are difficult for a beginner, and that there is no such thing as maximum time to solo (or license) in a civil training environment;
(2) groans, cringing, etc. are NEVER appropriate;
(3) safety comes first, but always remember that learning to fly is supposed to be fun;
(4) if you become frustrated with a student's ham-fistedness or lack of progress, the appropriate remedy is to tactfully arrange for them to fly with a different instructor;
(5) only after at least two, and preferably three, different instructors have formed the carefully considered opinion that a student is 'hopeless' (as is true in a small minority of cases) should the student be counselled that he or she may want to pursue other interests. Obviously, this discussion should be carried out in private and without any suggestion that the hapless student is a bad person or that anyone who can't learn to fly is stupid or personally inadequate.
That's my two cents. I recently qualified as a glider instructor, so let's see if I practice what I preach (talk is cheap!).
Pianorak, congratulations on your accomplishment! No doubt there will be further trying times ahead (as there are for all students except a very few 'naturals'), but keep your chin up, you now know that your persistance will eventually pay off.