> Do you believe that food can become an arbitrarily small proportion of the economy

This is not necessary at all for economic growth to be infinite. Food prices can "inflate" and so stay at, let's say 20%, of the economy while the amount of physical food being produced remains flat year after year. That's sort of what's happening with housing, education, and healthcare already.

I think seeing prices go up like this makes people unhappy, but what really matters is what portion of a person's income this stuff occupies.