But the goalposts haven't moved at all. There's simply a vendor on the sidelines selling rocket boots for 25 cents. Its not like these games start you off on a path, tell you "oh, once you've played for X long you'll be able to get Y," and then changing it so that once you get to X you find out that you also have to spend a dollar to get Y (some of these games might, but the ones I've played haven't, they've all been very clear up front what costs money and what doesn't). Most of them don't even make it so that you can't get to the goalposts without paying money, they just make it take considerably longer.

I fail to see how charging money for faster progress is taking advantage of idiocy. As another example, look at television programming. I can get a half dozen broadcast channels for free. If I want more, and want to get more out of my tv watching experience by having more choice in it, I have to pay for cable, who then offers me various packages, depending on how much each of those channels is worth to me.

It doesn't make it idiocy to value things differently than other people. I value $10 a month more than HBO. Does that make all of the people who pay for HBO idiots? Does that make all it blackmail for the cable company to offer a trial of HBO when I sign up (admittedly, that practice is slightly shady, due to the difficulty to stop the channels after the trial, but that is a completely different issue)? Just because you put more value on your money than others do on a shiny digital fish doesn't make them an idiot, it makes them someone who values shiny digital fish.

-To your edit:

Well, if that was the way things were from the start, sure. Say you go to the arcade, and pick out your game to play. To make this all fit well, lets pick tetris. As long as you know from the start there are various "powerups" you can buy throughout the game, it seems totally fair. Its 1 quarter to start the game. Later in, you can buy various powerups, like double points for one level for another quarter, or the ability to choose your next block for a quarter.

Does it make things different? Yes. But it certainly doesn't make them unfair. The options are open to everyone, those at the top and those trying to get there. Its fair, but is a little shady.