Why are the psychological forces that stop us from attaining Nibbana greater/stronger than those propel us towards Nibbana? Why is it that the psychological forces like lust, greed, desire, unskilful emotions, etc, which take us away from Nibbana feel so strong and have greater pull than the forces that propel us towards Nibbana like metta, vipassana (insight), etc?
Instinct (refer to  AN 7.11). The Earth today has 7.7 billion people plus zillions of animals, insects, fish &amp; other life forms. This whole Earth is created by lust &amp; craving (refer to SN 12.44). Basically, each creature is born from reproduction for the purpose to further engage in reproduction. It goes on &amp; on like this, endlessly for the unenlightened (refer to SN 15.1), until the Earth burns up.