Hi forzendiablo

I can assure you that we are not a ponzi scheme. And while we can not guarantee that each individual borrower will pay back, our repayment rates are 87% and if you diversify well you should be able to create a great return. You can have a look at our stats page to see the returns that are possible: https://btcjam.com/stats

I strongly recommend diversifying into 50+ different loans to avoid being pulled down by any individual user.
Here are recommended ways to invest on the platform: http://blog.btcjam.com/post/75934926878/the-3-rules-of-peer-to-peer-lending-for-investors

And here's a 1 hour video of me explaining the platform and how to use it:
https://www.youtube.com/watch?v=p9fvxhVH1pc

let me know if you have any further questions

Flavio/BTCJamads