Because Kali is "for hackers". Well its for pentesting, but for some thats not a difference.
#1 There will be next to no support regarding any problems you might encounter with Kali. You allready struggle to install bitcoin core, as you apparently have to build it yourself on kali. On almost any other Linux you could just download a prebuild and be fine.
#2 With an "Hacker OS" you might attract attention of (other) hackers.
#3 Single user allways root is against the basic principle of linux security. It is a good idea that you dont have allways full rights to change everything when you are just browsing the internet. If you want to sniff packets of the network you need root access, if you want to open myfunnywebpage.com you dont and you shouldnt have.
Install a "regular Linux" for all I care install Arch or Gentoo if you want to learn a lot. Get an USB stick and a small screwdriver to unplug your harddrive for the times you want to mess around with Kali.
Thank you.