Hello.
This is very wrong, I must say. People ho know they are going to get hypnotized and believe it get hypnotized. Those who resist and don’t want it, can’t get hypnotized. Just a note 
You have doubts, because you know that if you say that you’re going to have a lucid dream and you don’t, you will lose belief and hope.
This is a natural thing, happens to many people.
When you doubt something, you give your brain the information that you probably can’t do it, that you’re just saying something because you’d like it to work.
Hopefully, this will helps you. I hope it does!