If children with selective mutism continue to be mute, some of them finally think living with mutism is a lifestyle they elect (mutism identity), for instance, "I decided to do nothing to creative until I got to be able to speak. (case 22)"
I can partly sympathize with him. When I had selective mutism, I gradually thought my mutism was an identity.
That was a hindrance for me to overcome my selective mutism, because suppose my mutism was an identity, disappearing mutism meant I lose my identity. So, it was fearful for me to overcome selective mutism.
But I didn't know selective mutism at that time. If I knew I didn't speak because I suffered from an anxiety disorder "selective mutism," maybe I didn't think my mutism was an identy. But I would have thought my mutism was a kind of mental illness that could be treated.
This is just my case. I don't know whether other children or young people with prolonged mutism also think mutism as their identity.
[Reference]
Araki, F. (1979). Some psychopathological observations on mutism originating in childhood. Japanese Journal of Child Psychiatry, 20(5), 290-304.
Index of SM in Japan