"I'm curious about the motivation behind wishing to perform *publicly*, something you're not motivated enough to get right for *yourself*? Why would anyone wish to do it?"

From my own personal observation one reason why people do it is, what I call,'spouse encouragement'. Person X may be a good singer but X's wife or hubby can't sing a note. Nevertheless, X thinks, "I'm sure if I encourage him/her indoors enough he/she could be as good as me." So X pushes and cajoles spousywousy into having a go. Alas, the initial hypothesis often turns out to be false - but several long, long years later the long-suffering folk club audience is still having to live with the dire consequences on a weekly, fortnightly or monthly basis.