I have seen Worldcoin people scanning eyes in many shopping malls, they even asked me if I wanted to do it, my answer was a firm no. People, as a general rule, give away their privacy, you just have to look at what Google or Meta do, for example. In the case of Worldcoin it is the same, in exchange for a few dollars they scan your iris, and tell people that this data will be deleted, what they do not say is that they keep the hashes that can be used to compare future scans.
The reason why people do this is always the same, for money, ignorance of technology and, some, for having cryptocurrencies even knowing what they do. What Worldcoin users do is pay a very expensive price.