On the painfulness of sense pleasures: MN 75
https://suttacentral.net/mn75/en/bodhi
“Suppose, Māgandiya, there was a leper with sores and blisters on his limbs, being devoured by worms, scratching the scabs off the openings of his wounds with his nails, cauterising his body over a burning charcoal pit. Then his friends and companions, his kinsmen and relatives, brought a physician to treat him. The physician would make medicine for him, and by means of that medicine the man would be cured of his leprosy and would become well and happy, independent, master of himself, able to go where he likes. Then two strong men would seize him by both arms and drag him towards a burning charcoal pit. What do you think, Māgandiya? Would that man twist his body this way and that?”
“Yes, Master Gotama. Why is that? Because that fire is indeed painful to touch, hot, and scorching.”
“What do you think, Māgandiya? Is it only now that that fire is painful to touch, hot, and scorching, or previously too was that fire painful to touch, hot, and scorching?”
“Master Gotama, that fire is now painful to touch, hot, and scorching, and previously too that fire was painful to touch, hot, and scorching. For when that man was a leper with sores and blisters on his limbs, being devoured by worms, scratching the scabs off the openings of his wounds with his nails, his faculties were impaired; thus, though the fire was actually painful to touch, he acquired a mistaken perception of it as pleasant.”
“So too, Māgandiya, in the past sensual pleasures were painful to touch, hot, and scorching; in the future sensual pleasures will be painful to touch, hot, and scorching; and now at present sensual pleasures are painful to touch, hot, and scorching. But these beings who are not free from lust for sensual pleasures, who are devoured by craving for sensual pleasures, who burn with fever for sensual pleasures, have faculties that are impaired; thus, though sensual pleasures are actually painful to touch, they acquire a mistaken perception of them as pleasant.