Beppi has provided a concise and well thought out answer. To expound on it there is a lot of competition from chain stores for food, cloths, house hold items, electronics etc. One can go to Ikea for good furniture. Or look online for further deals. So most necessities are relatively cheap. Once one wants brand names then things get more expensive. Eating out cost more than cooking oneself but it is also relative. One can often find a simple, cheap Turkish or Asian restaurant where they can get a good meal for say 6 to 8 Euros – or one can go to a fancy restaurant and spend multiple times as much for basically the same thing.
For people on a super limited budget there are websites where one can simply ask for things and people donate them. Or there is what is called Sperrmüll where people throw out things that don’t fit in the normal garbage containers like furniture, household items etc. that they no longer want and it gets picked up and trashed. Of course lots of broken worthless things go out with the Sperrmüll but also lots of perfectly good things. The reason is that especially in the cities, people tend to have limited space for storage and they haven’t the time or energy to sell or even donate things to charity organizations. Thus, they just throw out perfectly usable things. Want some skis? No problem, people buy fancy new ones and throw out the old ones even though they are perfectly good; furniture, dishes etc. are abundant. I personally would not want to take someone’s old mattress or used underwear but nothing wrong with taking that retro lamp or ceramic flower pot or real wood cabinet.
There are also many flea markets. There are some regular dealers that sell new things for relatively expensive and others that sell things for very cheap, chances being they took a lot of the stuff from Sperrmüll themselves. Weekly flea markets tend to have more expensive dealers while yearly or occasional ones often attract people just trying to clear out their unneeded junk and wanting to get rid of their stuff for whatever price they can get.
The biggest cost factor for most people is going to be accommodation. Finding a good place for an affordable price gets more difficult all of the time and one simply needs some luck. There is always a tradeoff. One might find a relatively cheap place but then what condition is it in? Is it by a noisy street and far away from public transportation, schools and shopping opportunities? One’s personal situation will determine which factors are important. If one works at home, has no kids and has a car then they might find a bargain in a small village or outskirts of a city where others would hesitate to live.