how does a bail bondsman make money?

Answer 1

He charges you to put up bail.

When you show up in court, the bail money is refunded to the bondsman, but he keeps the fee.

Answer 2

Example:
Your bond is 10,000. You have to pay the bondsman 1000 to 1500 (10 -15% of the bail). They pay the 10,000 to the courts for you and when you show up in court, they get the 10,000 back and have your amount too. So they have 10,500 - 11,000. Pretty sweet.