Why use ready-made solutions?

Question

Programming

Why do many now prefer to use ready-made solutions?

At the moment I am writing Routing for my project, and although it would be possible to take it ready, but for myself I have extracted the following:
1. My current class does everything necessary.
2. I know every detail of my class and can supplement and change it at any time.
3. The number of lines is much less, while everything is the same.
4. And perhaps most importantly, I discovered a lot of new things for myself and I feel growth in my specialty.

Using a ready-made solution, you will not get the following advantages, and here's why:
1. It will take much more time to completely disassemble a ready-made solution for its subsequent improvement.
2. Maybe there will be an improvement, but only a theory, but due to practice (I rewrote many times from scratch, changed the structure ...) I learned a lot of new things.
3. Using ready-made code, I am in one system that is almost impossible to get off.

I would like to listen to constructive criticism and have a small discussion, in any case, I am a beginner and build an opinion based on my knowledge.

And I would like to answer the following points in advance:
1. Saving time. Enough to write and then integrate into your projects...
2. The right decision. I agree, but if you practice your skills, can't you do the same?

Answer 1

When I started, everywhere they suggested taking a ready-made solution, and not inventing your own miracle ...

There are two polar and at the same time correct points of view.
You have to write your own to learn (as you describe in the question). And to understand how ready-made solutions work and why .
It is necessary to use ready-made in work. Your craft, if you have little experience, will be of little functionality, unsupported by other developers and, most likely, full of holes and will not have tests. All this is important in the world of real development.

1. Save time. It is enough to write and then integrate into your projects...

"It is enough to write" is usually measured for bicycles in years, taking into account more and more new requirements and bugs found.

2. The right decision. I agree, but if you practice your skills, can't you do the same?

Again, it's about years of practice.