Everyone donated because mtrlt led them to believe his miner was going to be faster than hpX. He knew this wasn't the case and he knew that certain people were going to leak his code. Yet, he kept accepting "donations" up until the very end, September 2nd.
If he had any decency, he would have said, "I know all of you donated in hopes that the gpu miner would be faster than hpX. Unfortunately, (due to whatever reason, personal issues, lack of time, too hard), the software I produced is slower than hpX. Therefore, I'm giving back everyone's money, because the "early beta access" that I promised is now worthless, because you can get better performance out of hp10."
Who in their right mind would want "early beta access" to an inferior miner?
If individuals wanted to give him donations in return for nothing, because he put time into coding a miner. Then, that's one thing. But, that's not how he marketed it. He was giving "early beta access" in return for donations. He knew the miner was inferior before he released it. Why would he release it before it was capable of providing the "early beta access" advantage to the people who supported him?
How much did you donate that you wanted your bitcoins back?