I think what happened here is, some users have figured out that buying massive amounts of tickets increase your odds to win big amounts. They tried several times and succeeded a few times. They might have lost more times than what they have won. We do not see the times when these users buy huge amounts of tickets and lost everything. There are also some users with HUGE referral networks... and if these users are active, they get a lot of FREE tickets for every round. { Receive 1 ticket for every roll your referrals play } 
Exactly. And for those who say that there is 5,348,264 registered users and it is impossible that some users have won 2 or 4 times I want to say NO, it is not impossible considering the number of tickets those users buy. I, for one, disabled my lottery to receive reward points instead of lottery tickets so it is no wonder that I never win in the lottery. Many others, even if they haven't disabled the lottery, never buy additional tickets, so those who buy hundreds of thousands or even millions of tickets increase their chances to win by thousands times and no wonder that they win more frequently then others.
That said, I'm not encouraging anyone to buy more lottery tickets in order to have more chances to win. Kprawn said it right: they might have lost more than what they have won, we don't know about that.
