With real money one could go after the money mule (or dumb scammer) through their bank account. Maybe Google could be liable if the victim paid through Google Pay, but I somewhat doubt that Google Pay will let you transfer half a million. In this case, the victim's choice of virtual currency makes it very difficult to find the criminals. I don't see why Google would need to pay up for that.

I suppose it's always worth a try to sue Google, because there's nobody else to sue.