I do. If you value apples more than what you want to give me in exchange, and I agree with that, the value for you has increased (because you lost something you valued less, and you gained something you valued more, namely an apple)
You are talking about establishing a market value of apples. If you created economic value of apples when selling it, then who created their economic value when you bought them? If I buy an apple in exchange for something else, its economic value to me remains the same. I just exchanged it for something that I value less.
No, "market value" is PRICE, and has not much to do with value.
Value is satisfaction. Price is the exchange rate in a market (for instance, apples for eggs).
Suppose that to me, I value an apple more than 9 eggs, but less than 10 eggs.
Suppose that to you, you value an apple more than 3 eggs, but less than 4 eggs.
Now, there are still many other people exchanging apples for eggs, and when offer meets demand, we have the price. Suppose the price is 6 eggs for an apple. So the price of an apple is 6 eggs in the market.
As I value an apple more than 9 eggs, if I buy an apple, I have a value creation of more than 3 eggs in doing so (the apple was worth 9 eggs to me, and I could get it at the market price of 6). If you sell your apple on the market, you win more than 2 eggs in value in doing so: the apple you lost was worth less than 4 eggs to you, and on the market you could get 6 eggs for your apple.
So if you sell an apple, and I buy an apple on the market where offer and demand resulted in a price of 6 eggs for an apple, you won 2 eggs in value, and I won 3 eggs in value.
You and me selling and buying an apple resulted in a "total value creation" (I'm adding here different subjective values to different subjects which is in principle not done, but ok) of 5 eggs "out of nothing" because of our individual appreciations of an apple.
Of course, on the price level, there's obviously no "gain". You sold an apple for 6 eggs, and I bought one for 6 eggs. That's because price doesn't measure value, but only exchange rate.
Price does result from the subjective values of different actors in the market, but only indirectly, where offer meets demand.