why does suffering exist? One way to look at it is, we are infinite & immortal, & we choose to exist in order to experience ourselves in full. This includes experiencing those aspects of ourselves that frighten & trouble us: malice, deception, cruelty, etc. Being infinite & immortal, we are in no ultimate danger, no matter what happens to us in form. We always emerge beyond death & our ultimate nature is untouched by occurrence. This gives us the freedom to experience the entirety of ourselves, ugliness & all.
Another outlook is, we live to mature as souls. To progress from self-centered & fear-based to open-hearted & love-based. To experience this truly, we must know pain & darkness. We must experience the horrors & difficulties of the fear-based way in order to fully appreciate them. Only after this may we consciously choose the more loving path. We do so without a sense of worthiness or superiority. After all, we've been horrible ourselves. Instead, we choose the wiser path as a form of generosity to ourselves & our world, viscerally aware of the benefits this way provides, & viscerally aware of the suffering the other way generates. That visceral awareness is the gift of experience. & the cost of that gift is the crucible of terrible suffering.