Have you ever had a viral moment that turned into a loss instead of growth?

An influencer with 200,000 followers called the app a "hidden gem." By the next morning there were 15,000 signups. By 10 AM the database locked up and users were getting 502 errors trying to log in. 18 hours went into upgrading and scaling. By the time the site was stable the damage was done most of those 15,000 people never came back. The traffic was a gift the infrastructure turned into a loss. What would you need to fix before you'd want 15,000 people to show up tomorrow?