One of the big keys is to keep building your stack throughout a tournament, so you don't get to the point where you're constantly less than 10xBB later in tournaments. Because like you say, once you get to that point, there's a ton of luck involved.

I may reach that point if I lose a big pot deep in a tournament or something, but I also don't remain at that point for long. I'll either go bust or double up, and then use to use that to build a big stack again, so I won't have to worry about being so short stacked later on.

Its a really small sample size obviously, but I'm guessing that you aren't playing aggressively enough once the blinds get rather substantial, which also explains your high cash rate. Its relatively easy to fold your way into the money once you build a decent stack, its just not that profitable long term. Once you get a stack, you need to keep building on it through aggressive play.

However, picking good spots to be aggressive, and minimizing your risks to losing big pots is the hard part. You really need experience to do this very well.