The majority of online casino players are more than likely betting standard stakes.
EG
VP - Probably 1.25 to a maximum of 10.00
SLOTS - 0.45 to a maximum of around 9.00
BJ - 2.00 - 50.00ish
Whilst there are a minority of players that will play the MAX LIMITS on a regular basis. These players could be Company Directors, Footballers, City Slickers etc etc.
This is why their names appear more often than others. I think Ladbrokes only show winners that have hit 2500+ on one spin or hit, so it only makes sense that the high roller's names will always appear on this list.