I assume 10% is to low, but sites that promise 130%- 150% will bankrupt more faster.

You can earn a good profit with 10%.

Lets see, you play 10 times, you will get the double:
Example:

You join with 0.10 btc:
if you play 10 times one day you will get %100 profit or be, the double. So you still playing, you dont lose your 0.10 and will making profit with the 0.10 you earned from the site.

If you have strategies to play ponzi, you can earn a good profit with ponzi system.

Thanks.