WHO did he endanger?
He (the dog owner) could've been overcome by smoke which would have meant a firefighter would've had to risk his life to go in there and get him.
He had every Right to risk his own life.
A firefighter's job is risky enough.
The *riskiest* thing most firefighters do on a daily basis is get in their cars and drive, (which is also the riskiest thing most folks do in their lives). Yes, it's a dangerous job but they spend $$$$ on top-notch equipment, and the smart ones don't take unnessasary risks.
On average, about 100 firefighters are killed on-duty every year in the US. So, you are correct, the drive to work is one of the more dangerous things they do every day.