But it is much riskier for the fruadster after 1 transaction. With 0 confirmations it is almost certian that a new transaction with a higher fee will replace the older one. With 1 confirmation you have to either swing a lot of mining power or hope that your block becomes orphaned. The fraud likely doesn't make sense anymore if you lose your money 24/25 times instead of almost never.

Then Steam can accept that lower risk and mitigate further by then revoking game access.