1. Every Rick is born equal, but not every Rick is currently equal.
Ricks are all as smart as eachother, because they were the same at birth. However, their vastly different lives have created differences between them, which leads to cast differences between the Ricks as we know them.
You see the same happen to Morty. The "cop Morty" has become indifferent to Morty suffering, he is remarkable different from the other Morties.
2. Equally smart Ricks can still disagree.
Even if Ricks are equally smart, that doesn't mean they all have the same opinion. Our Rick, who is assumed to be as smart as the Council members themselves, disagrees about the usefulness of making a council (our Rick specifically mentions that the Council of Ricks have become the bureaucracy that they wanted to escape from).
3. Rick leads a risky life.
Take S02E03, Auto Erotic Assimilation, as an example.
Our Rick had a crazy drugs-and-booze-fueled orgy with Unity, but it ended after a while. Due to the multiverse, there likely exists a Rick who never stopped the crazy drugs-and-booze-fueled orgy (maybe with someone else if Unity still left him).
This Rick would likely end up in a different place than our Rick. His increased drug and alcohol usage may render his brain physically different, or he may end up different through his life experiences (compared to our Rick), or both.
Another example, S01E09, Something Ricked This Way Comes.
Our Rick was smart enough to see that the microscope he got from the devil would have literally made him retarded (I'm siding with Rick here). Due to the multiverse, there's likely a Rick who did not realize this and used the microscope.
This Rick would end up similar to Doofus Rick, i.e. vastly different from our Rick.
Another example, S01E06, Rick Potion No. 9.
This one is interesting, because here, our Rick was the one who made the mistake (Cronenberging the world). Due to the multiverse, there's bound to be a Rick who actually managed to not Cronenberg his world.
Another example, also from S01E06, Rick Potion No. 9.
There's also a third Rick here, one who we actually see: The Rick that blows himself up (and our Rick ends up taking his place).
Both our Rick and explosion Rick (for lack of a better name) are equally smart, yet one of them killed himself in an experiment and one of them (our Rick) has not.
All of these examples proves the point that just because you are equally smart, does not mean your life turns out the same way.
If your life turns out differently, you will end up in a different place (emotionally, physically, morally), which means that your life paths have diverged.
4. Rick does what he wants and doesn't care what others think of him.
Even though Ricks were born equal, their lives have not been the same. They've all had different experiences, they've all learned different things.
Rick doesn't care about social status. Notice how our Rick never really bothers to compare his life to that of anyone else, and he never spends any time trying to be the best (he simply is the best). If Rick is indifferent to his social status on Earth, it makes sense that Rick is also indifferent to his social status on the Citadel.
You're also succumbing to confirmation bias here.
My question is why won't unhappy Ricks just leave the Citadel of Ricks [...] ?
How do you know that the unhappy Ricks haven't already left? It's likely that the only Ricks who we see on the Citadel are Ricks who are happy enough to be there.
The Rick who takes Simple Rick hostage and asks for a portal gun, who I'm naming "desperate Rick", had a change of heart. At the beginning, he was perfectly happy in his life, but what he experienced made him feel disenfranchised and want to escape his dreary life.
The Citadel police pass this off with the line "same old story, Ricks/Mortys killing Ricks/Mortys."
Think about it.
Desperate Rick ends up dead, and the police pass it off as "a Rick killing Ricks". The way they say it reveals that it's nothing new, it happens constantly.
Let's say that every day, there's a Rick who "wakes up" and wants to leave the Citadel.
- If he's successful, we never see him again (on the Citadel).
- If he's not successful, he'll become desperate just like the desperate Rick we saw.
Maybe "a Rick killing Ricks" constantly happens, because there's constantly a Rick who fails at escaping the Citadel and then becomes another desperate Rick.
5. Some direct answers
We can also see in this episode that a Rick tried to make portal fluid (which is illegal in the citadel) but his "math was off" and ended up disintegrating because of it.
This is nothing out of the ordinary. "Methy Rick" undertook a risky experiment (just like all Ricks), contrary to local legislature (every Rick is a contrarian at heart), and ended up killing himself (just like Explosion Rick from Rick Potion No. 9).
Methy Rick's behavior is completely in line with every other Rick. It just so happens that this particular Rick found himself in the exact situation of being stuck on the Citadel and wanting portal fluid for some unspecified reason.
But he still acted like a Rick.
In the episode 'Ricklantis Mixup' a factory worker almost escapes the citadel by taking Simple Rick hostage and demanding a portal gun and he claimed to be 'more Rick' than anyone else.
Thinking you're the Rickiest Rick is nothing new, our Rick has argued the same about himself.
(Evil) Morty stated in his campaign speech that "every Rick in the citadel is just as Rick as each other".
It's a campaign speech. That means it's what they want to hear, not necessarily the actual truth.
If anything, the fact that Morty gets elected based on his adherence to the equality of Ricks, highly suggests that before Morty's election, the general atmosphere was that of an institutionalized inequality between Ricks.
I just cannot comprehend how you can build a society where a genius is happy to be a janitor.
Why is any human happy to be a janitor on Earth? Why is anyone happy to have the position that they have?
The simple answer is because they feel it's the best life they can have.
The same can be true of Ricks. It's statistically likely for some Ricks to exist who either:
- are incapable of complex tasks (e.g. braindamaged from adventures, bad experiments, drug and alcohol abuse).
- are smart enough to automate the work (though janitorbots) and end up having to do little to no work themselves.
- are happy enough to do a menial job in return for being able to live on the Citadel.
- are getting older and want a simpler life, no more risky adventuring.