Gambler's fallacy
Also said as Due for a win, Law of averages
Believing that a run of one outcome makes the other more likely next, when each roll is independent. After five misses, a true 50% shot is still 50%.
Your players will believe this however good your random numbers are. Tversky and Kahneman described the root in 1971 as a belief that small samples should look like the whole. That is why fair randomness feels broken, and why many games quietly stop being fair.
Say it
“Players are reporting the drops as bugged. Keep the 10% average, but add a counter that raises the odds after each miss and guarantees a drop by 25 tries.”
Where you’ve seen it
XCOM's players routinely complain about missing several 80% shots in a row, even though with enough shots that is bound to happen to someone.
Not to be confused with pity timer
The fallacy is wrongly believing a game has memory. A pity timer gives it one, so believing a win is due is then correct.