About 50 homeless people live at the Frankfurt airport. It’s a public space, they can’t be kicked out. It’s heated, and open 24 hours a day — so no need to leave at closing time.
Here’s a news report in German focusing on one man who has been there over two years. He collects cans for the deposit money, earning about 7 euros a day.
In a similar situation I think I’d try to mock up an online account showing frequent flyer status, match over to Star Gold, and buy a refundable airline ticket. Or really save up and buy the cheapest changeable business class ticket possible Then I’d eat free for a year like this guy did, and even have access to complimentary showers.