It may be that the person that relishes in their selfishness is actually more altruistic.

On that note it is also true that altruism is in fact a selfish trait.  To feel that your sacrifice means more to others than it actually does is a grandiose attitude. It only serves the self.  Altruism without love is only selfish. Love is the gap, the missing ingredient that serves justice to altruism making a sacrifice toward others.

Ego

Ego is inherently a feeling of self originating in the physical realm. You may feel like you deserve something, are owed something, are something.  This is all an illusion as you are no different than anyone else. It is the perception from the cockpit of our minds. We feel in control. Ego makes you feel good when you feel others are listening to you.  Unfortunately, no one cares how much you know until they know how much you care. Ego is a very easy thing to observe.  Most of what we say to each other stems from the Ego.
”It is the nature of the ego to take, and the nature of the spirit to share.”
~ Proverb
There are only so many reasons a person has to open his mouth at all.
  • To express something - singing, poetry, stories, art.
  • To impress - establish the idea of self investment to others.
  • To feel important - Everyone wants to feel significant.
  • To warn - Universal among all critters that can make noise.
“Wise men talk because they have something to say; Fools, because they have to say something.”
Plato
Detail of The School of Athens by Raffaello Sa...
Detail of The School of Athens by Raffaello Sanzio, 1509, showing Plato (left) and Aristotle (right) (Photo credit: Wikipedia)
Once you realize how much of what you say stems from ego, the less you will find yourself talking. Instead you will find yourself listening.  Truly listening.  Listening to the reasons someone is barking, instead of the bark itself.  You will learn that when people criticize you, it says more about them than you. It says they are scared, intimidated, or jealous of you. The only way criticism will be received is by love. People will only care about your criticism if they think you care, or if they want you to care.

Either way you look at it, building your own ego will only end in despair.
Pride comes before the fall.

Manipulation

If you think no one is trying to manipulate you, you are in denial. Manipulations are all around us. Sometimes we are manipulating the manipulators. This is also known among many as the "Game". Where players are players and there are no winners, just takers.
“Everything that deceives may be said to enchant.”
~ Plato
The next time someone does something intentionally to cause you pain.  Consider the notion that they may be betting on a reaction from you. You can even bet your ass that playing along will put you on the losing side of the battle.

Flattery

People that compliment you out of context, exaggerate your accomplishments, and build your ego up may have ulterior motives.

"I can live for two months on a good compliment" ~ Mark Twain

You will be drawn to people who make you feel good about yourself.  It is easy to do.  You may even think you are a partner to this person.  They will always say just enough to make sure you return to them for more.

Not everyone that compliments the job you do are complimenting the job, but the fact that you are doing it and not them.

Cruelty 

Not everyone causes harm for the same reason. It is my belief that this is within a persons soul.  A normal person will become angry if they are harmed physically or emotionally. This anger can empower them to inflict pain on others with a great satisfaction and vengeance. Anger can heal and go away, meanness can not.

Pleasure in the power over others can manifest in many ways. Power and love are often confused.

Honesty without kindness is cruelty.

The ones that are the hardest to love usually need it the most.

Deserve

Deserve is a word of opinion.  Someones judgment implying the rights were already given.  Much like the word entitlement.  Who is using this word and what they give or take from you using it is all based on a judgment.

de·serve
dəˈzərv/
verb
verb: deserve; 3rd person present: deserves; past tense: deserved; past participle: deserved; gerund or present participle: deserving
  1. do something or have or show qualities worthy of (reward or punishment).
    "the referee deserves a pat on the back for his bravery"
    synonyms:meritearnwarrantratejustify, be worthy of, be entitled to, have a right to, be qualified for More

Origin
Middle English: from Old French deservir, from Latin deservire ‘serve well or zealously.’


There are some things that you do have and no one else deserves to take them. Such as your honesty, integrity, and dignity.  People will often try and take these away citing that you are not worthy of them. They can only take them from you if you believe they are right when they tell you you do not deserve them.

Listening

It is dangerous to believe that the noise coming out of peoples mouths is nonsense and babble. Take into consideration what is being said, then consider the source. Consider motives, and desires.  You will find people more interesting than they even know. They will also tell you more than you ever wanted to know.

When someone compliments you or criticizes you.  You will be able to detach from the statement and instead understand why THIS person complimented or criticized you.
A flatterer is a friend who is your inferior, or pretends to be so.
~Aristotle
Resources:
30 Red Flags You Are With a Manipulator.
https://www.psychopathfree.com/content.php?212-30-Red-Flags