Around 10 percent of the world population can be hypnotized and not everyone is a willing subject.
To be able to be hypnotized you must be a willing subject and want to be hypnotized.
If someone just randomly tried to hypnotize someone it would not work because that person is not willing at the time to be hypnotized.
Everyone's brain is wired differently and some peoples brains allow them to be hypnotized while others do not allow them to be hypnotized.
So not everyone can be hypnotized even if the person is willing to be hypnotized but willing to be hypnotized makes it easier for the person to enter hypnosis.