antavat tu phalaṁ teṣāṁ tad bhavaty alpa-medhasām devān deva-yajo yānti mad-bhaktā yānti mām api

antavat tu phalam tesam
tad bhavaty alpa-medhasam
devan deva-yajo yanti
mad-bhakta yanti mam api

"Men of small intelligence worship the demigods, and their fruits are limited and temporary. Those who worship the demigods go to the planets of the demigods, but My devotees ultimately reach My supreme planet." (Bg. 7.23)

Demigod worship is meant for unintelligent men because the benefits derived from demigod worship are all material, temporary and retractable. It is also stated in the Hari-bhakti-vilasa ():