Cause Squid has given us the Rivalry that we love. He moves and gets a new job bye bye to the show. Logically speaking I don't know perhaps no other boss would tolerate his work ethic.
This. He quit his job in one episode. When Spongebob sees him again, he's living on the street. He tried selling his paintings, but said nobody would take them, so he had to eat them.
So while Squid hates his job, it, or jobs like it, are the only things he can do. He's a mediocre artist by Bikini Bottom's standards.
I always had the feeling that Squidward wanted to be an artist before anything else, so he never bothered to learn how to do anything. That'd make him unskilled labor so he'd be stuck at something like a factory or fast food restaurant, and even then Squidward sucks at his job. We see in the Krusty Krab Training Video, Hooky and Pickles that Squidward doesn't remotely know how to cook anything, slacks off and barely does his job at the register.
It could very well be that anyone else would be smart enough to not work for someone as cheap as Mr. Krabs, but Mr. Krabs is puts up with Squidward's p!ss-poor performance because Squidward is willing to work for such low pay since there's no one else who'd be willing to hire a slacker like him. Just look at how much Squidward takes advantage of Spongebob when he lets the pr!ck live in his house after living on the streets.
The biggest problem for Squidward is that if he were to find another job, it'd be something art-related, and no matter how much he denies it, Squidward sucks at just about everything having to do with art. Sculpture, music, painting, dance, everything Squidward does is absolute perfection in his eyes but to both normal people and art critics (like in Artist Unknown) his work is absolute trash.
As someone else said, Squidward did try quitting and ended up unemployed because he both couldn't find someone else to hire his lazy @$$ and couldn't find anyone who'd buy his crappy artwork. Odds are the experience would encourage Squidward to not quit EVER AGAIN, no matter what Mr. Krabs does. That could also be the reason Squidward went on strike instead of finding another job, he knows his odds are better arguing at the Krusty Krab instead of finding a new job altogether.
In a way Squidward and art remind me of Japanophiles (referred to on the Internet as "weeaboos"). They really want to be a part of a certain culture, wear all the clothes, decorate their house and rub it in everyone else' faces, but compared to the actual culture they just end up looking like an @$$.
Can't be too careful with all those weirdos running around.
I was always surprised that Plankton never tried to recruit Squidward to help him gain access to the Krabby Patty formula.
Even if Squidward didn't know what it was, there must've been ways for him to have access to it. If Squidward really hated his job that much, he would've had no loyalty to it. Plankton could bribe him to find out. If it was enough money, Squidward could retire from the job he hated, and stick it to Mr. Krabb in the process.