The problem here is quite simply the advertising effect. It simply sounds much more enticing to players if you distribute a large amount among a few players than a small amount among many players. 2k is not so much in the "western" world that it attracts many players, but 10k is definitely the case.
But as you can see here ... there are pros and cons for all types and implementation variants of the lotteries
I mean it's a no brainer to win a larger amount but knowing that the player base is so huge, it dilutes the chances.
After all, even if it's 1 winner for 250 grand, you'd see hundreds of thousands of entries but by involving more players, Roobet get to "buy back" more if you know what I'm saying. Just like spending that amount to get back 1,10 or 20 customers.
Lemme tell you a true story. I won a smart phone worth around USD 300 from a gambling site a few months back from a contest I wasn't even aware of. Definitely lesser than $2,000 but because of that incident, I started playing on that site daily ever since.
