Am I missing something? Retail seems way more profitable than exchange or contracts

My fellow Sim Companies players, hi!

I'm a new player in this game. Also, English is not my native language, and I will be graduating from high school soon, so I don't have much business experience. I have a question about this game (Sim Companies), specifically about producing a product and selling it (via the exchange market, through contracts, or retail).

My question is: "From what I've seen, selling a product in retail is more beneficial than selling it on the exchange market or through a contract. So what is the point of selling through those other methods (market and contract)?" Please share your experience!

For example, I produce 4,000 units of cement. The sourcing cost is $21,463 and the cost per unit is $5.3. The production took 12+ hours.

•If I sell through a contract, I have to sell below the market price (MP) of $6, for example at $5.5 or $5.4 per unit. If I secure a contract at that price, I would earn around $22k, meaning my net profit would be less than $1k.

•If I sell on the exchange, the competitive price is around $6.2 per unit. I would earn $24,800, giving me a net profit of about $3.3k and that doesn't even include transportation costs.

•If I sell through retail (a hardware store), it takes a much longer time. The retail price for cement is $13.6 per unit. After selling everything, I would earn $54k+, with no additional costs like transportation. That gives me a net profit of $32.9k over the sourcing cost.

So why would anyone choose the exchange or contracts over retail? Looking forward to your answers!