No, that is not how it is, you gamble lets say 100 satoshis and you gamble on 99% chance of winning (or was it 98% I forgot) that means for every 100 bets you will lose 1 time, now that is the average.
As far as I know, betting on 1.01x payout gives you 98% win chance, so you can lose 2 times within 100 bets, and that's important.
So, if you end up with one loss then you still bet on 99% chance of winning, that doesn't change, you still have 1% chance of losing but this time you gamble on 100k satoshi instead of 100, now of course you can still lose but that doesn't mean that you will lose, there is a 99% chance of winning, could it be a loss?
Yes, it perfectly can. I myself won with two 99x payouts in a row several times on various dice sites, so I know that two losses in a row are possible too.
Now, imagine what happens on this particular site, if you follow the strategy you described. After loosing 0.00025 BTC(min bet on Rocketpot), you place 0.025 BTC bet, and, although you have 98% of winning that bet, you can also lose it right away. And then, what to do next? Not to mention that I would not recommend depositing 0.025 BTC on any site to gamble with it.