I think spending 30+% of income on food is perfectly sensible, while spending more than 10% on shelter is complete madness. A house is built and stays there for decades without any extra work, yet even the most primitive house in industrialized nations is more expensive than an extremely advanced motorcycle that can go 200mph without breaking apart. Anybody can build a house by himself with primitive tools, trees and stones, given some time. Almost nobody can build a motorcycle by himself, even with advanced precision tools and all instructions given. Not to mention computers, cars and cell phones, which are tremendously advanced.

Considering the labour and resources needed to grow food, compared to the labour and resources needed to build houses, food should be much more of our expenses while housing should be much less.