Why is Trader Joes so profitable?

Could you elaborate on the reasons behind Trader Joe's remarkable profitability? How does their unique business model and strategies contribute to their success in the highly competitive retail industry? Are there any key factors that set them apart from their competitors, such as their product selection, pricing strategy, or customer service? Additionally, have they made any strategic investments or partnerships that have helped bolster their profitability? I'm curious to understand the key drivers behind their success and how they have managed to maintain their profitability over time.