Why did Vine shut down?

Vine was shut down mainly because Twitter decided it was not a sustainable business.

The main reasons were:

• Weak monetization: Vine was extremely popular, but it never developed a reliable way for the platform or its creators to earn enough money.
• Creator migration: Many major creators left for YouTube, Instagram, and Snapchat, where they could monetize their audiences more effectively.
• Competition: Short-form video features from rival platforms made it easier for users and creators to move elsewhere.
• Twitter’s financial pressure: Twitter was dealing with stagnant growth and financial pressure in 2016, so it cut products that were expensive to support and not generating enough revenue.
• Product and leadership issues: Vine also had problems with direction and delays in building features creators wanted.

So, in short: Vine shut down because it was culturally influential, but it was not financially sustainable enough for Twitter to keep investing in it.