Membership of Yakuza gangs shrunk to 30,500 from 184,000 in the early 1960s. Yakuza control Japan’s drug and sex industries and thus earned a reasonable living. As a result of

• Ongoing police crackdown on organized crime
• Communities no longer afraid of gangs and forced groups to close offices in residential districts
• Prefectural governments setting up programs that provides financial assistance to gangsters who want to get a legitimate job
• It has also become illegal for business owners to pay protection money to gangs
• Yakuza kingpin is also now legally responsible when one of his underlings kills or injures another person

Source: https://www.telegraph.co.uk/news/2019/03/29/yakuza-membership-sinks-record-low-ageing-gangsters-japan-retire/