I think that retiring before 50 is not the solution to unemployment after 50, although the idea of living frugally so you can retire early seems great until you try it.
33 * Cost of Living / (Salary - Cost of Living)
Assuming for simplicity 3% real interest on investments once you stop working (which is close enough if you're trying to get out of the rat race quickly), and potentially infinite lifespan.
So if your cost of living is $10k and you earn $100k you get:
330,000 / 90,000 -> less than four years.
Great theory.
I don't want to live on oatmeal and tuna for the rest of my life. (I actually don't think we should be eating tuna at all and have stopped eating it although I love it.)
Now aside from obvious (e.g. kids, as you state) there's also:
* At some point you'll get a $500 optical bill or a $5000 dental bill (or a $50,000 medical bill if you live in the US) -- and let's not even get into chronic conditions.
* You may want to travel.
* At some point there will probably be a major economic shock and you may be utterly screwed. (But hey, so will a lot of people, and you'll be used to it.)
Finally -- you may enjoy working. I do.
While some people go the route of eating oatmeal and tuna every day, there are plenty of routes to financial independence that don't involve living a life devoid of nice things. It's less about never working again and more about having the freedom to choose what you want to do -- whether that's work for yourself without worrying about paying rent or working full time for someone else.
200 CHF for food might sound little but I actually eat way healthier than most of my colleagues. (The last thing you can afford in Switzerland is getting sick.)