And yet no one is going to give you a substantial salary rise unless you sign a resignation letter.
All that questions about the reason why someone wants to leave during recruitment or exit interview are a ceremonial, and people are answering with polite bullshit.
Yes, I'm looking for a new job to get more experience, to grow, to get new challenges. Not because I want more money and we all know it is the easiest way to get it. Not because I have an idiot manager. Etc..