I totally get your frustration and I think you are right to be upset. But on the other hand, it's all about probability and randomness generation within the game that makes this highly unlikely event happen once in a while.
I think of the game engine as a set of algorithms that are full of random stuff generation with forced percentages on it. Let's say like playing Risk, where you can invade a country and throw 3 dices against 1 for as many times in a row as your army can. And yes, it can happen that the defending player who left an unprotected territory gets lucky with the dice every time and the smart attacker that did everything to make sure he wins the match loses his army.
We tend to complain about things that go unplanned without taking a good look at all the times things went well. Let's check how many of those games were won by the worst side and we'll see if there's room to complain or if we were just unlucky.
The doctor may tell you that you have a 99% of chances of coming out alive of surgery and you could easily be the guy out of 100 that dies, and the doctor didn't necessarily lie.