Don't assume Cambridge is a cheap place. I live in Boston area and I can tell you housing cost in Cambridge is crazy as well.
A one-bedroom apartment is at least $1500 per month and easily over $2000, so students cannot afford to live alone. Boston is one of the most expensive cities in the US too.
Hi I'm also waiting for Columbia PhD and have no result yet.
It drives me mad because I am a foreign national currently working in the US, and need to submit my work visa application before April 1 if I am not attending any school.
I already have a master's degree so I am only applying for PhD. Let's keep each other updated.