Most cards limit how much cash you can get. Even if you have, say, a $10,000 credit limit, you might be limited to $2,000 in cash withdrawals. How to get around that:
1. Go to www.squareup.com.
2. Get a free Square card reader.
3. Connect your Square account to your bank account.
4. When the reader comes in the mail, plug it into your phone.
5. Swipe your credit card through the reader, and charge it with the amount of cash you need.
6. The cash goes into your bank account the next day.
Square charges a 3% fee, but since the charge is classified as a “purchase”, there’s no low limit, no cash advance fee and no higher interest rate.
(Disclaimer: Rational Conspiracy has no affiliation with Square.)
The Rationalist Conspiracy 
This is a violation of the Square terms of service, and if done non-negligibly will likely lead to your Square account being frozen/closed. See http://boardingarea.com/blogs/frequentmiler/2011/11/03/a-quick-note-about-square/ .