It's impossible to find the private keys of existing bitcoin wallets unless they're brain wallets, so this project is a false claim. As we say in cryptography, the probability of this event is negligible. For comparison, it's more profitable to just use your computer for mining. It's actually also more profitable to physically use your computer as a hammer to physically mine in your garden in the hope of finding gold.
There are bad ways to create bitcoin private keys besides brainwallets. Broken PRNGs being one of them, and keys people have deliberately made weak being another.