Passive income: NO

Earning passive income solely from rental costumes as a side hustle is unlikely for most people. While it can be profitable, managing inventory, customer inquiries, and logistics typically require ongoing effort. To potentially make it more passive, one could invest in automation tools for online bookings, hire staff for customer service, and optimize inventory management systems. However, achieving true passive income where minimal effort is required would be challenging. Most individuals may need to continually be involved in the day-to-day operations. While some outliers may achieve a more passive setup, it's not the norm. Misleading expectations may arise from stories of passive income without highlighting the initial hard work and ongoing maintenance needed. Realistically, full passivity may be more achievable for those willing to invest significantly in outsourcing and automation, but it's not a guaranteed outcome.