Surely most people who experience
relative deprivation will likely feel upset or believe that they have been treated unfairly. Much of that feeling may be from instinct and/or may be a
rationalization of their greed, envy or normal desire for more which they can have regardless of whether the deprivation is truly unfair or unreasonable.
As for the example given, I suspect we do not have enough information to determine whether the deprivation was 'unfair' or unreasonable or whether the feeling of being treated unfairly is correct or unreasonable itself.
Any other example of the same problem might likely succumb to the same problem. I suspect this is because there is a strong tendency, which permeates both in the telling of the story, the lack of specification of crucial details and the interpretation and conclusion-jumping of the reader of the story, towards false dichotomies.
To illustrate, one reading such a story, might somewhat unconsciously model the situation as comprising of only two options with Option A being realized. For instance, Person 1 might think the only options are:
A. He gets the magical PDA (let's say with a market value of $1,000), but the others get the smartphones (each with let's say a market value of $10,000).
B. He gets the smartphone and the others all get the smartphone.
Of course, he prefers B to A. B is better by a utilitarian measure; B is better for him by a selfish/greedy measure; B seems to be agreeably more fair. So he is upset that A has occurred rather than B. The problem is that the choice between A and B is a false dichotomy, and the fallacy is that he concludes simply that
A is unfair without qualification when what he means is that
A is less fair than B.
Now, let's say we have Person 2 who encounters the same situation with A being realized, but he thinks the only options are:
A. He gets the magical PDA (let's say with a market value of $1,000), but the others get the smartphones (each with let's say a market value of $10,000).
C. Nobody gets any smartphones or PDAs.
Generally, this person will prefer A to C. A is better than C by a utilitarian measure; A is better for him by a selfish/greedy measure. Whether or not C is fairer or not is arguable mostly because 'fair' is equivocal and vague, but it also may be moot since there is agreement on the other two points -- which is better by a utilitarian measure and which is better by a selfish measure. So probably Person 2 is happy that A happened rather than C. But like with person 1 this is a fallacy because it is a false dichotomy.
The details might make either Person A's or Person B's false dichotomy more reasonable simply by creating a context in which either C or B seemed more likely as the runner-up option or in which it is the focus of one's attention, such as that a person is happy overall but is upset with a specific person/circumstance that specifically caused one of strictly two things to happen.
In any case, we can only say what would be a reasonable reaction to A to the degree we know the circumstances that determined A over other options and the detailed context in which one is considering those determinations matter.
While there is countless if not infinite other possibilities in a modal sense, in addition to the ones I mentioned, we at least want to take time to consider the following as well:
D. Everyone gets PDAs.
D. D is worse than B both by a utilitarian measure and by a selfish measure. D is better than C bother by a utilitarian and a selfish measure. D is arguably equally fair to C and B, and all three (D, C, and B) are arguably more fair than A; but since fair is equivocal and vague it's also arguable that fairness is tinged with the same factors as a utilitarian and/or selfish measure such that B is fairer than D and D is fairer than C, with A falling somewhere in between but being less fair than B.
In short, the real question that determines whether the distribution of spoils is unfair and whether whether it is reasonable to "feel wronged" whatever that means and that
helps determines whether one will indeed be upset is
why exactly did A happen rather than something more like B, C or D or any other relevantly distinct possibility and is there a context to the judgement (e.g. if we ask the Plantiff in a civil court case whether he felt he was treated unfairly the context tells us we only mean in regards to the modal dichotomies generated by other actions done by the defendant, not to include optimistic reactions regarding modal possibilities that the defendant of which the defendant had no or negligible influence).