Veto became an Abnormality through the key but unlike the rest of those that attained it through genetics from an Abnormality down their lineage but this was different.
He had hoped to be like Superman and this manifested itself meaning he had all the abilities of superman but it was unknown if the weakness applied.
It took little to no time for Veto to start flying and before he knew it, he understood what just happened to him but now he looked at the key with horror but for some reason could not bring himself to rip it off of him.
He felt intoxicated by it, it felt like an addiction that he could not get rid of because he understood the concept of the key or rather began to understand it.
It materialized his hopes in the physical world but this made him conscious of what goes through his mind as all it took was a destructive thought but he could not deny his life had gotten astronomically better since getting the key and he could not deny it.