Final answer:
Otaku are mainly from the middle class due to their disposable income and historical patterns of spending on leisure and cultural pursuits, reflecting a cultural legacy and modern consumer behavior in Japan.
Step-by-step explanation:
The concept of otaku being mainly members of the middle class is rooted in their economic ability to engage in leisure activities that require disposable income. Historically, in Tokugawa society, merchants, who were essentially the middle class, accrued considerable financial power. Regulations restricted their social mobility, so they channeled their resources into literary and artistic endeavors, creating a vibrant culture around the ephemeral world of ukiyo. This appreciation for arts and culture has persisted into modern times, where middle-class families support specialized hobbies and interests. Comfortable middle-class incomes allow parents to invest in the specific talents and interests of their children, such as arts lessons or other hobbies akin to the otaku culture. This can also be observed in the consumer behavior of modern Japan where, despite high costs of living, the youth prioritize convenience and consumer amenities.