On what gambling site did you play crash and get higher multipliers? Was it in this site? But, better if we shouldn't be overconfident because the experience might change when we are now in the real thing. It's usually normal to get higher multipliers if you are playing with small bets but the moment you increased your bets, that's the time you will get screwed.
I have played crash on a lot of sites and to be honest, I have won a much higher multiplier but not on this site. If I'm correct, one was in flush.com. I don't know from what you are saying that with a high amount of stake, the chance of a higher multiplier is low. Is it true in a provably fair game? I don't know. I have very minimal knowledge of this but from what I understand, this is not possible to manipulate when the stake amount is higher or lower. The result will be the same regardless of the stake amount.
Anyway, as I said, I always play small bets. In crash games, if I'm correct, the maximum I have tried was 0.01 LTC, can't remember the exact worth of that either.