It's 12.2 gb of program, why does it take up 44gb to install?

The 12.2GBs installer app has compressed all of the files necessary to install macOS Ben Hur.

As it uncompresses them for the install it needs the space on your hard drive to do this.

The install of Ben Hur will overwrite your existing macOS but to be able to do this

it needs the free space on your mac so it can write the files to disk and then shuffle them around

to overwrite your existing system without loss of data.

At the end of the install you will notice that not all of the 45Gbs has been used and has been re-allocated as free space.

No need for you to get so angry.

Hey again! Agree with the responses. I do believe the first response was complete and accurate. And this is a public community, not Apple insiders, but users of Apple products like you, who have needed help in the past, and try to give that same help back if we can, that’s what I like about this place. But if you need to, you can contact Apple Support directly, I’m sure they’d be ready, willing and happy to help out!:

https://support.apple.com/en-us/HT201232

Hope it works out okay!

Agreed! It’s just temporary, purgeable storage that is needed, all though it’s more than previous OS’, it’s necessary. I like that, “Mac OS Ben Hur”! Next OS? Mac OS Spartacus!

The no sense of humour boys have been in.

Touché

That wasn't a reference to you, it was because a reply I made was removed.

I know, all good man! 😆