I don't think this is strange. People mostly use these cards to pay for online subscriptions, such as buying game credits or subscribing to Netflix. Some services automatically try to spend the funds from your card when the package expires. If the funds are insufficient, the service keeps trying to renew your subscription until it succeeds. I assume he subscribed to something and turned on the auto-renewal, which triggered multiple attempts to spend the funds from the card. I am sure people do not keep large funds on such cards.