most animals aren't smart enough to conceptualize reality, they just follow their instincts and react to stimuli animals that sleep 16 hours a day aren't lazing off because it's comfortable, they're reserving energy for the situations they need it for. jacking off is for higher life forms that have excess energy and can draw enjoyment from multitude of sources rather than just sating their needs. most people who masturbate do it because it's fun not because they're compelled to, though the natural inclination is there
Finland