Exactly. The vast majority of people prefer to re-use code that has been battle-tested by use in thousands of other projects, where bugs have been found and fixed.

This isn't to say that they're perfect or bug-free, but they generally don't just save time but increase the quality of your final product.

Writing your own implementation of third-party functionality that already exists has its place, but it's generally something you implement later as an optimization for very specific reasons.