So, Shrī Krishna says in the Gita,
विहाय कामान्य: सर्वान्पुमांश्चरति नि:स्पृह: | निर्ममो निरहङ्कार: स शान्तिमधिगच्छति ||
Vihāya kāmānyaḥ sarvān pumānśh charati niḥspṛihaḥ. Nirmamo nirahankāraḥ sa śhāntim adhigachchhati.- Gita 2.71
काम एष क्रोध एष रजोगुणसमुद्भव: | महाशनो महापाप्मा विद्ध्येनमिह वैरिणम् ||
Kām eṣh krodh eṣh rajoguṇa-samudbhavaḥ. Mahāśhano mahā-pāpmā viddhyenam iha vairiṇam.- Gita 3.37
So, Shri Krishna tells us in the Gita that there are three gates leading to the hell of self-destruction. What are they? Desires, anger and greed. This is what Shri Krishna tells us and out of these three, the most detrimental to our being is desires.
यदा सर्वे प्रमुच्यन्ते कामा येऽस्य हृदि श्रिताः । अथ मर्त्योऽमृतो भवत्यत्र ब्रह्म समश्नुते ॥
Yadā sarve pramuchyante kāmā ye’sya hṛidi śhritāḥ. Atha martyo’mṛto bhavatyatra brahma samaśhnute.- Kathopaniṣad 2.3.14
So, the Upanishads describe that if, when an individual's desires are completely destroyed then he attains perfection and then thereafter there remains no need to gain any knowledge or practice devotion, practice spirituality whatsoever. And this is why when Prahlad was only five years of age, when he was granted a boon by Narsingh Bhagwan, he asked for something very unique.
यदि दास्यसि मे कामान्वरांस्त्वं वरदर्षभ । कामानां हृद्यसंरोहं भवतस्तु वृणे वरम् ॥
Yadi dāsyasi me kāmānvarāṁs tvaṁ varadarṣhabh. Kāmānāṁ hṛidyasaṁrohaṁ bhavatas tu vṛiṇe varam.- Bhagwatam 7.10.7
Ek var māṅgu Hari Govind Rādhe, māṅgane ki buddhi kabhu sapnehu nā de.
- Radha Govind Geet
So, Prahlad said, “My Lord, please I beg You to make me, if You want to grant a boon, yes, please make me desireless, please grace me so that the seed of desire that is within me may be destroyed forever!” This is what he asked for from the Lord. So, why are desires considered dangerous? The scriptures give us the answer
इन्द्रियाणि मन: प्राण आत्मा धर्मो धृतिर्मति: । ह्री: श्रीस्तेज: स्मृति: सत्यं यस्य नश्यन्ति जन्मना ॥
Indriyāṇi manaḥ prāṇ ātmā dharmo dhṛtir matiḥ. Hrīḥ śhrīs tejaḥ smṛitiḥ satyaṁ yasya naśhyanti janmanā.- Bhagwatam 7.10.8
So, as soon as a desire appears in one's consciousness it destroys all the noble faculties of an individual; the strength of his senses, his mind, his vital breath, vital energy, vital force and his body. He loses his sense of righteousness, determination, understanding good fortune, modesty, prowess and adherence to truth. This is what the scriptures describe.
