I'm looking for a single word representing the effect of something becoming progressively harder to 'hit' or succeed at, such as a gambling game in which you become less likely to win after each successive spin. Another example may be a boxer who becomes more evasive as a fight progresses.
That game offers diminishing returns with each successive spin.
The boxer became more evasive towards the end of the fight which led to diminishing returns for the fans who stayed up late hoping to see some action.
1. In economics, a yield rate (i.e., of profits, production, benefits, etc.) that fails to grow in proportion to the amount of investment, skill, time, or effort that is added. The restaurant, to combat high volumes of customers, hired a large surplus of wait staff and cooks. This led to diminishing returns, however, as the overcrowded staff was far less efficient and eventually cost the restaurant more in wages than it was earning.
2. By extension, any output or results (e.g., of a product, project, organization, etc.) that fail to increase proportionally to additional time, money, skill, or effort. Unfortunately, the show's charm has not lasted, and the infusion of zanier plots has created diminishing returns in terms of quality.
— Farlex Dictionary of Idioms
'Facing Exponential-Odds' comes to mind.
While defining both "exponential" and "odds" would take a whole pile of words, I do think people are familiar enough with the concept. They understand it when a sports announcer says something like "with every moment of time that elapses the odds of overcoming the score deficit become exponentially higher"
3) rising or expanding at a steady and usually rapid rate: a city experiencing exponential growth.
Sisyphus was the God cursed to constantly push the boulder up the hill, for it to only roll down to the bottom just as he reaches the top.
This captures the idea that as you get closer to success, you ultimately fail. Though this has connotations of never succeeding even once, whereas in the gambling example you gave, you do win some hands, it just gets harder each time.
of or relating to Sisyphus.
endless and unavailing, as labor or a task.
My first thought with the boxer was "hustle" - when a very skilled player of something bets with you and loses, increasing your confidence, and finally bets a huge amount and whoops you hard. But I don't think that's what you actually mean.
Russian roulette often takes this form - with each click, the odds of the next guy winning decrease (unless the guy in front of you shoots himself).
quicksand? It gets harder to get out the more you struggle. I don't know how true this really is.
a Catch-22 is a situation where you cannot win ever because of some loophole.
A pyramid scheme involves getting people to invest in a project and paying early investors with the money paid by later investors; it cannot pay off for everyone, and is least likely to pay off for the last people to join.