If you do the math, Bitpetite is really paying 1.11% per day to you as an investor. They charge people .5% (at least) to use the service. They need lots of deposits and withdrawals to help tumble the money. If look into bitcoin tumbling in general, it's very profitable for the business owner. They make a ton of money. That's why they won't shut down the website, unless they had to. I think it'll be around until we have more regulations regarding bitcoin.
RE: Thunderbit is Paying Out - Bitlake Bit the Dust - Bitpetite New Tumbler Service