A lot of startups nowadays will pay referral bonuses as an alternative to the typical employee/ marketing costs that involved to obtain customer acquisition. As long as you don’t value the info or whatever minutes it takes to signup then it’s “free”. Granted they’re much more legit than some guy pretending to send money via PayPal and providing a fake confirmation letter, lol.

Examples: MoneyLion (personal finance/mobile banking) gives up to $55 USD for free with promo $55FREE.
Draftkings does an extra $100 via referrals. Dave App to get advances.. cash app. Line App.. to send money.. Webull for stocks / crypto.. there’s a ton of them!