Why do People Litter?

I was at the beach this morning picking up garbage and I wondered to myself, why do people litter? Is it convenient? There were garbage cans every 50 feet, so I guess it's more likely to be willful ignorance than anything. It's ironic, people come to beach for its beauty, but they throw shit on the ground, do they do that at their own home? Well maybe, but at least they will cleanup after themselves after a while. I'm not a fan of fining people for stupid reasons, but if you litter, you should be fined. Some places already have hefty fines for littering, but they aren't enforced. Every beach needs at least one guard on duty to patrol for litterers. And cigarette butts aren't exempt! Those are the most numerous trash items I find and they stay around for a while. Smokers, you might think it's fun to temporarily toss your butt on the ground, but in a few decades, tarma will give you cancer!