Terrible austerities not prescribed by scripture do certain humans practice, endowed with hypocrisy and ego, impelled by the force of desire and passion.

Incorrect tapas. Aśāstra-vihitam — not prescribed by śāstra. Ghoram — terrible, extreme severity. These janaḥ practice (tapyante) tapaḥ — austerity.

Impure motivations: dambha-ahaṅkāra-saṃyuktāḥ — connected with hypocrisy and ego. Kāma-rāga-balānvitāḥ — impelled by the force (bala) of desire (kāma) and passion/attachment (rāga). The purpose is not purification but power, impression, or satisfaction of desires.