Like most gambling ventures, privateering generally did not pay off at all.

From the excellent Perilous Fight by Stephen Budiansky, an account of the naval aspects of the War of 1812. Page 288.

By the end of 1812 American privateers had brought in some 300 prizes, and a year later the total stood at 700. The trouble was that it was coming at a terrible price. Like most gambling ventures, privateering generally did not pay off at all. Of the five hundred commissions issued to private armed vessels throughout the war, more than three hundred never took a prize before returning home or being captured themselves. Privateers took an average of only 2.5 prizes apiece, a third as many as the average American navy ship. And because they most definitely operated on the “pecuniary system,” they did exactly the things that vastly reduced a commerce raider’s effectiveness, as William Jones had pointed out in his orders to American naval commanders: weakening their crews by manning their prizes and risking their recapture by trying to get them into friendly ports rather than burning or sinking them on the spot. Of the 2,500 prizes taken during the war by American warships and privateers, about 400 were burned, most by the U.S. navy; of the remaining 2,100, some 750 were recaptured before they could be brought into American or neutral ports as prizes.