Head, meet wall.
Wall, head.
There is no reason for your service to exist.
You don't provide a custom product, and you don't make an existing product easier to use.
Poloniex lending can be set to 2 days. Slightly longer than your site claims, but the money is definitely going to be there.
Same with most other margin exchanges.
So all you are doing is taking almost ALL the profits from lending, and leaving a small fraction for the user as their "profits".
Now, to compare this to freebitcoin.
You lose again.
They offer a comparable APR, and keep the money on site.
You can withdraw at any time.
It is very convenient.
It is trusted already.
The list goes on.
You are providing a lending service that already exists. Except yours is down some dark alley, with no witnesses.
There is a very good possibility that the coins will all vanish overnight.