https://www.siliconvalley.com/2024/06/22/the-hidden-cost-of-helping-friends-earn-more-credit-card-rewards/

Thanks to travel rewards credit cards, you summer like a celebrity for the cost of a staycation, and your friends are starting to notice. There’s no reason to gatekeep your travel secrets — the more friends know about how to earn valuable rewards, the more who will join you on epic and deeply discounted adventures.

Not only do you take the time to answer their credit card questions, but you also send referral links if you carry a card they’re interested in applying for. If they end up getting a card with your referral, they can earn a generous sign-up bonus by meeting the card’s spending requirement, and you get “paid” for your time and expertise by getting a referral bonus.