1. I work in the film industry on big studio movies. I work with lots of video and do some editing, though I am not the editor by trade (our editors work on desktop systems.)
2. I need portability, so no iMac. But when I'm in the office I can't wait to get a 5K display to use this with, and will be ordering one as soon as they're available :)
3. I own my own company, but all of our work is for bigger companies (studios.) I'm accountable for the purchase and paying for it, so it's not just a case of putting it on someone else's budget / expense account.
4. I do travel a lot, and I like having access to old cuts of movies, and a large library of reference no matter where I am. It's not that exciting, but the 2TB SSD was one of the most exciting reasons to upgrade for me. My previous MBP (bought in 2014) has 1TB and I'm feeling the pain of not enough storage.

I've previously been in that same position where a company didn't want to spring for a high-end computer. That's annoying, and one of the reasons I like owning my own company.