Trigger warning: racism, sexism, pedophilia, mention of war and bombing, suicide, violence, mention of domestic abuse, alcoholism, 5️⃣ mention of substance abuse.
One reason surely is that it's Japan's one legal outlet for gambling, allowing players to try their luck and 5️⃣ win money playing pachinko. In fact, during Japan's long economic downturn many turned to pachinko in a last ditch effort 5️⃣ to make ends meet.