So a guy at work saw our laptops running kali linux, and wanted the "Installer" for it..

And after few months when /root partition is full - backup data and format again 😂😂😂

Sorry but... What happened to "never give Kali to a novice who never used Linux, they will learn bad practices and use them to create security problems"?
I would have given them a Debian, the LFS and BLFS handbook and waited a week. The would-be hacker would be back to playing Watchdogs and you've had a major laugh. If he actually makes it through, he's got what it takes and deserves access to the proper tools (their code, for it is prudent to built from source) and may call himself an apprentice.
Anyone who thinks just installing Kali would make him a hacker is just another skiddie in the making.
Besides, he killed a Windows install. He should feel good about himself. But yeah, guided partitioning... Bad thing. Don't use.

@ilPinguino we work in the same field, he should know better.