If you buy this product for $100, you gain the use of it, at value U[30] to yourself. The workers who made it gain $80, at value U[80] to yourself, because of your utilitarian preferences. Total value U[110]
If the alternative was a product of cost $100, which you value the use of at U[105], but all the money goes to greedy rich people to be squandered, then you would choose the first.
If the alternative was spending $100 to do something insanely morally important, U[3^^^3], you would do that.
If the alternative was a product of cost $100, that was of value U[100] to yourself, and some of the money would go to people that weren’t that rich U[15], you would do that.
If you could give the money to people twice as desperate as the workers, at U[160], you would do that.
There are also good reasons why you might want to discourage monopolies. Any desire to do so is not included in the expected value calculations. But the basic principle is that utilitarianism can never tell you if some action is a good use of a resource, unless you tell it what else that resource could have been used for.
Firstly, you are confusing dollars and utils.
If you buy this product for $100, you gain the use of it, at value U[30] to yourself. The workers who made it gain $80, at value U[80] to yourself, because of your utilitarian preferences. Total value U[110]
If the alternative was a product of cost $100, which you value the use of at U[105], but all the money goes to greedy rich people to be squandered, then you would choose the first.
If the alternative was spending $100 to do something insanely morally important, U[3^^^3], you would do that.
If the alternative was a product of cost $100, that was of value U[100] to yourself, and some of the money would go to people that weren’t that rich U[15], you would do that.
If you could give the money to people twice as desperate as the workers, at U[160], you would do that.
There are also good reasons why you might want to discourage monopolies. Any desire to do so is not included in the expected value calculations. But the basic principle is that utilitarianism can never tell you if some action is a good use of a resource, unless you tell it what else that resource could have been used for.