These are not incompatible. Imagine a system where you have a 99% chance of winning $1 and a 1% chance of losing $200 and the total number of bets required is always less than 100. The house certainly has a huge edge. But the vast majority of people who use this system will win. And there can never be a "long run" because the total number of bets required by the system is always less than 100.