In To Kill a Mockingbird how does Boo sacrifice something for the good of Scout and Jem?

Boo Radley has been in the shadows for many many years. He not only risks his life to save Scount and Jen (from Bob Ewell), when he kills Bob, he risked, therefore sacrificing, his reputation. In a town like Maycomb, killing Bob would put Boo in the limelight. Everyone would want to thank him and talk to him, etc. That is why Mr. Heck Tate changed the story, which had nothing to do with Boo. He changed it to Bob falling on his knife, and excluding Boo from the story. Boo Radley can live life like he never killed a man.