A sense of purpose alone won't let you lodge in cities with high cost of living.

If anything, I dare say running a non-profit usually requires a lot more skills, especially people skills and passion than a tech job.

I'm not sure how it is in the US but in Europe there is this sense of entitlement when you talk to people that because you work at a non-profit you should work for free. If I give my valuable time to contribute to the world at large, I expect to be able to have decent living conditions.