The purpose of normalization is not to save storage. In fact it might often require more storage, since it involves introducing a foreign-key column. It really depends on the data in question whether it saves storage or require more.

That forign key column is saving duplicating multiple columns

But I don’t think that’s the top 5 reasons of normalization

Fair, I said one of the big benefits, not the purpose - in some cases it can require more storage (but that storage is often more amenable to compression) -but generally deduplicating your data doesn't increase your storage needs.