Compared to a small business the "big chains" might be able to operate with smaller profit margins, or have lower non-labor costs, or profit from owned real est

Compared to a small business the "big chains" might be able to operate with smaller profit margins, or have lower non-labor costs, or profit from owned real estate, but it isn't enough for long term viability. Excessive rents are going to turn any neighbourhood into a desert like South Kensington.