Hmm I’m not sure if Joe Biden’s was THAT severe. Regardless, by the way he speaks of it it seems like it highly impacted him when he was younger. In one of his videos he mentioned that what motivated him was knowing that he had so many other amazing qualities and the stutter was only a minute part of him that didn’t detract from these qualities. But to answer your question, Drew Lynch is a youtuber(comedian)with a severe stutter, might want to check him out!