Every buy slot has a max win cap, usually between 5000x and 30000x, and the cap applies to the total bonus payout, not per spin. On a bought feature this matters because the cap is measured against your base stake, not against the price you paid for the bonus. A 10000x cap on a 100x buy effectively means 100 times your outlay, which the cap table at https://thebonusbuyslots.com (https://thebonusbuyslots.com/) lays out clearly. Keep that ratio in mind when a game advertises a big headline figure.