So he didn't abandon family, and I don't know that he planned never to return to a life of luxury, and one can certainly criticize American adventurism in the Muslim world, even early 2000s Afghanistan, but Pat Tillman would fit this broader idea, and he paid for it. His parents were a lawyer and a teacher in San Jose, California. He was an unheralded college (American) football player who improved enough in his first few years in the NFL that he went from barely making the pro ranks to being thought of as a valuable contributor who'd have a long and (by any normal human standards) very lucrative career. In early 2002, his team offered him a contract extension worth several million dollars, but he turned it down to enlist as a soldier the US Army after 9/11.
He was known to be outspoken, thoughtful, well-read, and assertively non-religious. While he thought there was a moral case to be made for fighting the Taliban and Al Qaeda, he is reported to have called the Iraq War "fucking illegal." Still, for better or worse he did remain loyal to his commitments and deployed to Iraq. After, he finally went to Afghanistan. He was killed in a friendly fire incident that was covered up at every level, from his platoon-mates burning his uniform, body-armor, and personal journal, to the Pentagon claiming he was killed by enemy fire and coming up with an entire alternative scenario for how he died.
Even once the friendly fire was known, his legacy was being whitewashed to protect the legitimacy of the war and military recruiting, and his family had to fight not to have him remembered as a generic rah-rah "Patriot," but as a complicated man who thought about bigger issues and had a personal moral code not tied to generic notions of 'Murica, Jesus, and Apple Pie.