Winning 7k with $1k is kinda basic if you ask me, most people do that with simple bets without using any form of strategy that are complex... it's just x7 and that's pretty much achievable with minimal effort..and considering the fact that you did this for 35 days makes if stressful but the only advantage to this is the minimal risk involved.. splitting your bets into weeks or months can increase the chances of winning..But this doesn't mean that luck isn't involved, you can do everything right and still end up losing.
Very well possible to turn 1k to 7k using ordinary basics to bet the games, it will become a practice if you can repeat that winning consistently and not losing any at all, which eventually is not possible and anyone that has such a formula will never share them rather they keep making their money, but it's not possible to win against the house all the time that is why gambling is designed to favor the house.
Most time the thing that makes such a mindset is when a gambler wins a few games and his luck continues for some time, this could trigger such confidence in the gambler to think that he has developed a strategy whereas, in the end, he starts losing heavily again.