15 yr old wants to learn guitar only from YouTube. No classes, he says

Bought him a basic guitar in May after months of lobbying. He won't have a teacher, says YouTube is better and classes are 'for kids'. Three weeks in, he can play the first twenty seconds of four songs and nothing beyond that 🤷 Is that just how self-taught goes, or does he need someone for a few months to get past this stage? I play nothing myself so I can't judge.