You are always going to end up with gains at some point if you play long enough, all is to know when you are on a "lucky streak" and you have more chances to loose than win in the number of rolls you can play compared to what you gained so far.
Simply "quit while you're ahead"? Yes. That would be a smart move for any gambler. However it's incorrect that you will always end up with gains. Due to house edge and not having unlimited funds it's more likely that you will end up with losses.
If you want to play 1000 times and you're just ahead of 2% you can still have chances to do better, if you just did x3 after 2 rolls, it's very unlikely you're going to beat that unless you want to play a very long time

When you pay 1000 times, you need to consider how much money you will use, and I am not sure that you can win the games even if you use big money as the bet. About the chances, I don't think that the opportunity to win will bigger too because no matter what strategy you use, you need a lucky streak to win. I agree that we need to quit while we can, so we don't risk more money in gambling.
The more monney you can bet, the higher are the chances to win.
If you play 1000 times 1 on the dice, you are still going to win a certain number of times, there are statistically good chances that you will be above at some point, all is too see how much can reasonably expect to gain with the 1000 rolls and stopping when it get close to that.