100% code coverage. Is it worth?

Last week I wrote an article for how to build Casino app with React and Redux for the first time: My impression of building Casino web application with React and Redux .

But it was missing tests for some parts, and I decided to cover that part also and to achieve 80% code coverage.

And at the end it's came to be 100%. Check repo

The question is : Is it worth it in real project to have 100% code coverage?

By my opinion is a bit to much waisting time, because there were a parts which were completely useless to test it.

Example: Placeholder Component which by my opinion doesn't need to be tested.

My Conclusion:

I would say that always is good to have code coverage and to achieve some kind of percentage, but most important is to be tested real scenarios and 100% code coverage doesn't mean that is fully tested