It's kind of amusing to see all the things you readily admit you don't know only for you to put your rather specific estimate of 3,600 hours. Neglecting challenges and events seems pretty dubious considering they look like they provide about half of the currency. Most of all though you're neglecting the fact you can simply unlock the guns in a crate. I unlocked all of the guns within a couple of hours of play, but 'the maths' suggests it should have taken me unlocking 160 chests to get them all. Maybe I got ridiculously lucky. Maybe the maths is bullshit. I know which I'm betting on!
I'm going to justify buying it on the basis that I really enjoy playing it
I'm not in love with the progression/crate system they've put in place but from what I have actually experienced in the beta I can comfortably tolerate it. I don't mind that people are upset about what they've put in place, but fake maths isn't a great way to fight back. Perhaps I'm an oddball for saying it, but I kind of loathe the progression systems in all of these games (one of the things I liked about OW was that it didn't have one). This really doesn't seem that much more arduous than having to level up in Call of Duty or grind to get attachments in Battlefield/operators in Rainbow Six, it's certainly not as annoying as trying to get cards for Warzone in Halo 5.