Krishna explains the 3 gateways to hell in Bhagavad-gita 16.21.
dvāraṁ nāśanam ātmanaḥ
kāmaḥ krodhas tathā lobhas
tasmād etat trayaṁ tyajet
“Threefold is this soul-ruining gateway to hell: lust, anger, and greed. Therefore one should give up these three.”
In this video, I’ll explain each of these three and the general idea of why these bring us so much suffering.