this not abusing , abusing would mean someone who has many accounts and buying the max tickets with all of his accounts
but if someone is buying the max tickets you can't call that abusing cause it's not against the rules
if the site has 10 players like dellwin it will cost the owners a lot of money
I would agree with that. He was making sensible bets with odds in his favour.
maybe enabling this lottery again in the future with like 100 tickets max per user can help the situation ( if you considered bringing them back of course )
I'd probably go with 1000 tickets. With the price of BTC going 10x in the last year that would be a logical adjustment.