Why does the same person keep winning the Potion Lottery? She won yesterday and she's won again today. She also has a brag sheet on her lookup showing she's won dozens of times in the past 2 years. I thought it was a random draw so how could it be that one person keeps winning...yet when we try to buy again from the main shops we get the error beast telling us to give everyone a chance. It just doesn't seem right.

That person buys something like 1400 tickets a day? (it's a specific number, it has some meaning to them iirc, but I don't know the exact details). Regardless, it's a lot of tickets so they have the best chance of winning.
It is a random draw but if a person buys a lot of chances in the potion lottery, it increases their chance of winning since their name will be entered once for each chance they purchase. (Someone else's name might still be picked, it's just less likely.) It isn't necessarily profitable to do this, because the potion given away is random as well and there are only a few that would cover the cost. It isn't against the rules but I'll agree the system is a little unfair since it is possible to weight it in one's favor. It kinda works like most real world lotteries though so... -shrugs-