Literally no one "knows what they are doing." My deepest regret of my formative years is believing what adults say without them having a meaningful justification. While experience does exist in certain contexts, if someone says they "know what they're doing" particularly for things that don't have a concrete solvable answer (think how to solve a math problem vs. making some sort of philosophical or ideological judgement) they they ESPECIALLY don't know shit and you shouldn't trust them.