That's how people are. Helpers syndrom and most if not all coaches have it. We want to help others so badly, often more than they want.
In a way we violate their wish, because we believe we know what's better for them, which is in a way arrogant - unless you have their permission and wish to do exactly that.
It's a fine line to walk and even after hundreds of students you can't be perfect.
About your specific cases:
Sounds simply like you picked the wrong guys. Happens to all of us
There is always a reason why somebody is where he is right now. Emotional/mindset is very underestimated, but it is part of the equation and part of being a great poker player.
You can't say in sports "we are the better team, but lost bc we didn't pay attention in two spots" ... well that "paying attention" is part of the whole deal altho most humans fail to understand this.
People say Isildur would be the best player if he wouldn't tilt. Well, and i would be the richest man in the world if well, i had an IQ of 300. Would be could be should be.
Imo also a lot harder to fix than strategy in poker. You're talking about changing a person (hardware) vs changing strategy (software update).
It can be done, but it's the hardest part imo.