You don't, the reality is it's extremely unlikely this happens and if it does the worst outcome is high bandwidth use + the image doesn't load for everyone. Hardly the end of the world.

You can very easily host things on a paid server though, which these days cost very little, use another image host or S3/similar when if things went crazy popular.

> worst outcome is high bandwidth use + the image doesn't load for everyone. Hardly the end of the world.

No, the worst outcome is that your home internet connection is being effectively DDoSed.

You could probably apply some QoS on your router to minimize the effect, of course.

Free Cloudflare account

As I'm mentioning in other comments, then you wouldn't be hosting from home.