Sales yaay or naay

Working as area sales manager as a management trainee in FMCG start up. My Ceo says sales teaches life lessons and there are very few he has seen who did badly in sales but went onto succeed in life One year into it and I wonder why sales training is so essential. Yes perseverance and putting your ego down and learning to take No for an answer. But I still think too much is made of it. Most of the time is spent dealing with distributors who don't want to pay, outlets who basically want all stuff for free. Nobody cares about the brand value, sales story or pitch, product quality etc People with sales experience can you share some of your learnings here