Karl Marx posited the labor theory of value which said the value of anything — a commodity, a product or service — was solely determined by the labor that goes into it. It’s an interesting theory (that’s cost quite a few lives), but it doesn’t explain how people spend money.
If Marx were right, then a diamond or a rock found next to it would be of equal value. After all, they would be of equal value because of the labor miners put into it; yet you don’t see rocks in jewelry store displays. Raw land, which has no labor at all, trades every day for a fair market price.
If Marx were right, then the 20th slice of pizza you eat would be just as valuable as your first — yet we all know that over time what you consume becomes less valuable.
Marx didn’t consider the customer. He only looked at value from the labor side. The only place to go from his theory is to the correct narrative where value is subjective.
The theory of value that says nothing is intrinsically valuable, except human life. With products or services there is no intrinsic value; any value placed on them depends on the utility it provides the consumer.