What you're experiencing is the unreliability of random number generators on a smaller scale.
While a 75% drop rate sounds really good, and it normally is, the truth is that the 75% drop probably applies better to the entire player base way more than it does to individual players.
75% would be the average for certain but in order to get that average you need to have lots of drops and on the individual level we've only had 8, which is a tiny sample size and that means that the law of averages dictates that a chunk of players will have missed every drop.
With more drops no doubt everyone will get all the keys but the question is whether or not all the frustration will be worth it for those being forced to wait.
