> Then Worldcoin can guarantee/prove that one individual only has one wallet.

Which only works if you have somehow created a completely secure method proving the provenance of iris scan data. Given the intent is to lock a bunch of money behind this, I highly doubt that this is remotely possible.

If worldcoin has real value, someone will find a way to obtain and replay iris scans to make money.

Biometrics is simply not a good security mechanism.