Yes, Kali Linux is Safe to Use !!
My name is Pawan Chauhan and I’m using Kali Linux Operating System for 5 years, but I haven’t felt anything comfortable yet.
Kali Linux is 100% safe, So I recommend that If you are interested in learning programming or penetration testing, then you should use Kali Linux.
You can also read about Kali Linux vs Windows, and If you want to install Kali Linux on your Computer then you can learn about that How to Install Kali Linux on VMWare.