Premise:
- Verb 'want' is normally (?) stative
- We use adverbs when we have an action verb and adjectives when the verb is stative
In sentence "I want it bad(ly)" we would use the adverb 'badly' and not adjective 'bad' --> "I want it badly" (correct)
From that we can infer that the verb 'want' is then an action one. But is this really true? And what action does it describe here? Furthermore, where/when can we use 'want' as a stative verb then?