1) Starcraft Players
It's all about skill, pride, and being the best. Everything else comes 2nd to proving you're better than the next guy. I think this is generally what competitive gaming is all about.
2) Poker Players / Gamblers
They think more objectively and in terms of money and expectation. Pride and proving you are the best are sentiments you often need to leave behind to be a successful poker player.
So it's pretty easy to see why almost invariably every poker player understands the raise from 500 to 5k as just another objective decision and why a lot of starcraft players see it as a cowardly dodge.
To further illustrate this point from the perspective of a gambler I will offer a story from the most recent season of high stakes poker where Tom Dwan proposed a 500k vegetarian bet to Phil Ivey stating that if Ivey could go 1 year without eating any meat he'd win 500k off of Dwan. Would you become a vegetarian for a year if I paid you 500k? Of course you would, so would I. But Phil Ivey would not, it wasn't worth it to him and he countered by raising to 2 million dollars. 2 million was an amount large enough to motivate Ivey to become a vegetarian for a year while 500k was not enough. Similarly $500 is not an amount large enough to motivate me to practice 8 hours a day 30 games a day for a week but $5000 would have been.
Indeed, Idra is a worthy opponent and I wouldn't risk my pride as a starcraft player or my money as a gambler without giving myself serious preparation time. Afterall, Idra is a CJ pro gamer and his life is currently dedicated to this game; he's playing 8+ hours / 30+ games per day. Meanwhile I've been kinda busy gambling and organizing SC2 tourneys. When you take all of this into consideration, it's not really fair for anyone to expect a serious match or even a fair one at the drop of a hat.
Furthermore, this grudge match, it's terms, and whether or not both parties accept have nothing to do with my initial point that Idra is not the undefeatable player he's making himself out to be. Despite what some people have posted I never stated that I am currently more competitively viable than Idra and only cited a few of his recent losses and our win rate to prove the point that Idra is not an undefeatable player and in fact quite far from it. Yes, CauthonLuck did beat Idra 3-1, yes Fayth recently beat Idra in a ladder game, yes lzgamer has beaten Idra numerous times, and yes I did have a ~75% win rate vs Idra in season 1. None of these facts are up for question and this bo5 challenge of idra's was just his desperate response to hold onto the notion that he really is as great as he thinks he is.