Can this quote be used to justify some insane and/or evil crap? Yep. But it also perfectly captures Captain America: an incredibly stubborn man who (luckily for the rest of us) happens to have an exceptionally fine-tuned moral compass. While this speech is delivered by romantic interest Sharon Carter in the movie, it's adapted from a similar speech made by Cap himself in The Amazing Spider-Man #537 (2006). Considering that (ENDGAME SPOILERS AHEAD, as if you haven't watched that movie five times by now) Cap ultimately goes back in time and marries Sharon's aunt, maybe she originally heard it from him during one of their supremely awkward family dinners.
There are other great speeches that demonstrate why Steve Rogers calls himself Captain America and not Captain Federal Government of the United States of America, but no one has put it more succinctly than Frank Miller in Daredevil: Born Again: