Because it's a job. You sound like the sort of person who confuses the word 'job' with 'reason for living' or 'identity' or 'holy quest that should last your entire life.'
If someone wants to quit a job be it working at McDonalds, or being QB in the NFL or the world's highest paid porn star why wouldn't those of us in the working class support it? Providing, of course, that the person's fallback plan isn't mooching off of social programs when they could work otherwise which clearly isn't the case here...
I understand your characterization of the type of person you think I am, you are close. I actually enjoying working more than any other activity. Sleeping and relaxing really bores me. My down time is reading, else I am repairing engines, computers, windows you name it.
In saying all of that, I also like to rely on people to some extent and I think Luck quitted on his team, it is ok to phrase it that way, he did a good thing for himself, but there are two sides to this and I look at both. I have just spoken strongly on the team and fans part but I get Luck as well.
I was very annoyed with the timing but posters here have rasied valid consideration that I failed to consider in that Irsay may have known about his desires but kept a charade going until it was leaked.
People can quit anything they want, I don't have an issue, I have an issue when they are being praised and called courageous for doing that. As you said, it is a job, so if you quit/retire, it should be called that and nothing else. I know I used the word support, I was addressing the accolades actually and in hindsight, support was a poor choice of word.
NFL is a cruel business, they use you and then forget about you, so if you get enough to survive, get out while you can, but there is a right time for everything, Luck or the Colts mightly mismanaged this.