30% success rate? Well I assume it is worth it when you have lost a great deal of coins, but seems like a pretty low rate for me.
It's pretty high for something that's 'unhackable'.
You're getting this wrong, he won't be able to magically find the whole password, there are other services like this (You probably shouldn't trust ANY OF THEM) but for them to work you have to provide some part of your password and hints and based on those they can brute force the incomplete password.
He can't hack anybody's wallet without knowing some part of the password.
It is un-hackable.