I really think that the people here are being a bit hard on poor Katniss. Sure, she acted selfishly, and OK, maybe her mental instability was pretty obvious, but can you blame her? Right from an early age, she was forced to do what she had to, just to survive and keep her family together.
I'd defy anyone living in District 12 in her circumstances, under the rule of the Capitol, to play it any other way. Supporting a catatonic mother and a young sister (not to mention an ungrateful cat and a goat) isn't easy. Losing her father at such an early age would embitter anyone. And simply doing what most of us consider our natural right - supporting herself - was actually illegal, and she would have been made into an avox if she'd been caught.
And that's before the story even starts. After that - wow, how much space do I have? She sees her sister selected for the games, and has to volunteer. Has all sorts of nasty things happen to her in the arena. Has to deal with what she genuinely thinks is Peeta's fake love. Even when she wins, the system tries to cheat her out of it. Shall I go on, or do you get the picture?
And in the next two books things get even worse... by the end, she's a physical wreck, wracked with guilt, seen those she loves tortured or dead, and doesn't know what will happen to her after killing Coin.
In short, the first seventeen years of her life are no picnic, and I don't think anyone would have a "happy happy joy joy" philosophy after what happens to her.
And yet, throughout the books she still maintains her courage, integrity, sense of fairness, and pays her debts no matter what the cost.
She supports her family, at great risk to her own security. Volunteers to save her sister. Tries to protect Rue, Treats Rue with respect after her death, and risks the punishment of the Capitol. Mercy-kills Cato, when she'd be justified in letting him have a horrible death. Donates part of her victor's spoils to District 11. Goes into the Quarter Quell with the sole aim of saving Peeta's life, at the cost of her own. Agrees to lead a revolution, though she doesn't want to, to save those she loves. Fights courageously in the war. And finally, commits a supreme act of courage, killing Coin, fully expecting to be punished (probably executed) for it - just because to do so is the right thing!
And throughout, she chronicles what happens totally honestly, without making any excuses or sparing herself.
Sure, she can be a bit feisty or sarcastic at times, and OK, maybe she's a tad neurotic. But given what she achieves, the way she maintains her ethics despite huge temptation to turn her back on them, she never gives in. I salute her!
Hands off the girl on fire!