Statistics
You know what he is? A statistic.
Dirk Cresswell, Muggle-Born, died at the hands of unknown Death-Eaters. One of many.
Just another statistic. They didn't care that he was the reason the goblins hadn't rebelled or joined You-Know-Who.
He was only a statistic. They couldn't care less that he was the reason Dean Thomas and Griphook were still alive.
A statistic. Nobody cared that he had drawn the attention away from a small, fourteen-year-old witch, who was now somewhere in America, with distant relatives.
Who cares about a statistic, after all?