I think the author said 50,000 exactly because of that, if the man bought the tickets for 30 years in a row they shouldn't be that expensive so he didn't win much considering the prize is decided.
That wouldn't be suspicious seeing as how this is lin bai's first time betting on a lottery he would choose a number that someone has been betting on for the past 30 years so he would rather choose that one which would make sense.
