Why should you patent

This article that appeared in yesterday's The Hindu sums it in few words. Need any thing more?

"More than 100 million Kalashnikov rifles have been sold worldwide and they are in service with the armies of 106 countries, but Mr. Kalashnikov has not personally profited from his invention because it has never been patented. Today he supplements his salary and pension by patenting other products bearing his name, such as the Kalashnikov Vodka"