Be honest with yourself, when somebody told you their idea last time, how did you react?
Were you the good guy, and offered a reassurance, constructive feedback, and guidance? Or did you shrugg it off, or worse: mocked and ridiculed?
The thing about enthusiasm is that it’s not an infinite resource. It’s a little bit like a campfire. Sure it can start a wild forest fire and spread like an inferno, but when dampened and shunned, it will slowly fade away, and die.
If you’re in any position of leadeship, your role is to keep the fire of enthusiasm alive. Telling hey, I see your effort, it’s great, let’s go a little bit further, instead of well, that kinda sucks, lol.