I can see why you would perceive Schuster's manner in the way you have, and maybe there is a problem in that regard. Its however difficult to interpret motivation in other people because we tend to see things through our eyes and not theirs.
Some points though. Its most unlikely that a first grade footballer lacks at least a significant amount of ticker, hunger, dedication, otherwise they would never have reached the level they have. These guys are the cream, the top tier of the game and they would have had to work very hard and make many sacrifices to reach that level. How many of us could do that. How many of us have had the commitment in our particular fields to be the top tier of our professions.
The important issue to remember is they are all just like us emotionally They have their doubts, their fears, their disappointments. These things affect some more significantly than others. When things are working fine, confidence is up. Self belief reinforces our drive to do better. Pretty obvious that. Some of us are naturally more confident, more able to deal with the knocks. However, hit a bad patch, when everyone seems to be questioning your ability, resolve etc can affect confidence and drive. I suspect most of us have gone through down periods. Certainly I have and easy for self doubt, even depression to develop. Not easy to get back on track.
We're all different, despite similar range of feelings, in how we deal with those issues. I suspect, but I may be misinterpreting, that Schuster is a confidence person. You can read that in the comments he made about being the best in the World. You wouldn't say that unless you were trying to build up your own confidence. Remember what Spud is reported to have advised him. Don't read social media. He would only say that if he knew Schuster was being negatively affected by what is being written, and how vulnerable his confidence was.
Schuster will come good if he can avoid injury, and get the positive vides about how he's progressing. He's not like Burbo for example who has strong self belief, enough to say no to an upgrade at one stage to prove himself. Its not lack of resolve I suspect Schuster has, its lack of confidence.