It depends on the person.
Some people just want/need to be out of fine dining for(ever) a little while. I've taken off from a couple great fine dining jobs with the intentions of finding a less demanding restaurant job. It's strange being asked "are you sure you want this position?" or "why are you applying here when you could...?" I've done this before for a couple reasons, and both are for comfort.
1. It's nice to take a job knowing that nobody knows as much as you. They may know THAT restaurant better than you, but they don't know the different grades of Wagyu steak or how to prepare it Mi-Cuit. Chances are that nobody knows what a Txakolina is, nor can they even begin to name something as easy as the First Growths of Bordeaux. You have a confidence level that is hard to touch, and having confidence + knowledge is important for working in a restaurant.
2. Probably most importantl: If the money is good, why not? If a decent restaurant opens down the block, and you're currently commuting to your job, maybe making a little less money while dealing with less stress would appeal to you.
Some people just can't handle the stress of fine dining, and they naturally go back to something a little easier. This doesn't mean that fine dining is necessarily always a higher stressed environment (ALL restaurants have varying degrees of stress that usually start at "insufferable" and go up to "homicidal"), but fine dining requires a higher caliber of worker. You have to bring your A-game everyday whether you're sick, hungover or coping with a bad breakup. Going back to something casual can be a relief.
In fine dining, the expectations are as high as the bills we drop. You're expected to work 10+ hours AND study at home. You're fighting together for a Michelin Star(s). This is the game; the players are very wealthy/important; nothing can be off.
Working in restaurants is also different than other fields because it's pretty uncommon for someone to stick around much longer than 2-3 years. Some people stick it out for a year just so it doesn't look bad on their resume, even though they "checked out" months ago. Yes, there are definitely people who stay with their company a long time, but by the percentages, this is rare.
Also, leaving/finding a job isn't out of the ordinary, because we all sort of know each other. We drink/eat together, and it's common to be "poached" from another restaurant/bar. If I can consistently make $225/night slanging steaks to tourists from the same menu the restaurant had 20 years ago vs. $250/night keeping up with the nightly changes chef made, what country our Yellowfin tuna comes from, what silverware to place with that dish, which wine to pair with it plus where that wine comes from, what's the grape and which glass it's it served in... Sometimes it's just not worth the stress. (And sometimes that dish is off the menu the next day! A!)
Is it worth it? Absolutely! It's incredible to be part of a team in an amazing restaurant. You learn a lot and make great money. And when you leave, you (usually) start to miss it... We see food people have never heard of, and they probably can't pronounce. Our knowledge of wine, spirits and beer (even coffee and tea!) could probably get us a job teaching! Our tolerance for stress (mental & physical) is on a whole different level. But, I'm sure like with any profession, you have to balance your life with your work.
Leaving fine dining isn't really a "step back", but usually just a step in the right direction. Whether you can handle it or not is one thing, but whether you want to handle it is another.
