You can fetch a better rate by lending bitcoins on this forum. People get a rate as high as 3%-7% per week which is better and you can lend people with a good reputation to ensure the borrower is trustworthy.
The reason lending rates at Poloniex is actually low is because it offers much security for your coins. Once a deal is reached, everything becomes automated, you need not know who is borrowing your coins or ask for some collateral that might become end up an issue, the system simply secures your coins and promptly pay back without fail. The only way you can lose lending this way is only if Poloniex is hacked or becomes insolvent. If you ask me slow and steady most often wins the race.