I have another moral issue that I would like to discuss. If you're suffering, but someone else is suffering more than you, does that take away your right to think "my life sucks"? Furthermore, if you're happy, but someone else is suffering, does that make you selfish because you're gloating in your own happiness instead of trying to help the suffering person?
Let me answer by presenting my opinion on Duties and Prohibitions.
We often refer to rights both positive and negative.
Positive rights (if they exist) beget Duties in others to fulfill our positive rights.
Negative rights (if they exist) beget Prohibitions in others to prevent their infringing our negative rights.
All actions that are not prohibited or that prevent you from doing your duty are permissible.
Of all the rights I think we have, I can boil it down to 1 negative right from the theft of our time/life.
Yes, I do not believe that people have a positive right to life. Only a negative right to life.
Let us consider the interaction between a hypothetical positive right and the negative right to time.
The positive rights of others makes a demand on the time of the person infringing on the negative right to time.
Therefore no positive rights exist if the negative right to time exists.
Since all actions that are not prohibited or prevent you from doing your duty are permissible and duties do not exist, all actions that are not prohibited are permissible.
So any action that does not deprive another of their time/life (or what they are entitled to through voluntary trade of their time/life) is permissible.
So you never had a positive right to say "my life sucks" however unless doing so would deprive another of time/life, it is permissible.
In the case of the selfish (amoral term meaning looking out for the self) act of making yourself happy it is permissible provided doing so does not deprive another of time/life.
In fact, under my definitions of moral and immoral less than 10% of selfish acts preformed are immoral. (This is why I disagree with your assessment)
The above is the judgement based on my world view.
I would be interested in hearing what makes something moral or immoral in your mind. "What makes an act immoral?" This is an important philosophical question that too view people think about in-depth. This makes finding other opinions on the matter so valuable. (Hence my persistence)