All of the mechanisms surrounding you have a common source: the overarching fear of death (the annihilation of the ego). From the fear of death sprouts meaning, for meaning is a reassurance of the ego. The number-one priority of the ego, if it is not trying to survive or is distracted by a novelty, is to sustain a stable ecosystem in the mind.
Before you were born, others were struggling with the meaninglessness of existence. And so they built civilization, culture, social memes, etc to distract them from the possibility of death. To try to ignore the scream of impending doom.
So you were born into an environment that was already set up to deal with this fact of existence. Before you even knew of the meaninglessness of existence, you were exposed to apparent meaning. An entire society that focuses on establishing the ego as the microcosm of the world. You're so fucking important!
But then you start to get disillusioned with the game. You start to see cracks in the walls. And thus you have your first (of many) existential crises. If you do not succumb to the crisis, you build yourself back up. You mind meaning in the suffering. You find purpose in a purposeless universe.
For most people, it's enough for them to submerge themselves back into the collective insanity of society. Others need more personal meaning. But everyone who is a functionally-"healthy" human being finds some way to deal with the meaninglessness.
What is most disturbing is that it seems that most people forget why they even had to build this thing call culture or meaning in the first place. They forget the origins of their angst.
They forget that their meaning was fertilized by meaninglessness. They look at the flower without looking at its roots. The flower might be beautiful, encouraging, deep, meaningful, or what have you. But we must not forget that the only reason this flower is this way is because of where is came from. And where is came from is not beautiful, deep, meaningful, or anything like that. We can't forget that meaning is a reaction to an undesirable state.