Windows as a software package would have never been affordable to individuals or local-level orgs in countries like India and Bangladesh (especially in the 2000's) that are now powerhouses of IT. Same for many SE Asian, Eastern European, African and LatinoAmerican countries as well.
Had the OS been too difficult to pirate, educators and local institutions in these countries would have certainly shifted to Linux and the like. The fact that Windows could be pirated easily is the main factor that led to its ubiquity and allowed it to become a household name. Its rapid popularity in the '00s and early '10s cemented its status as the PC operating system. It is probably the same for Microsoft Office as well (it is still a part of many schools' standard curricula).
The fact that Windows still remains pirateable to this day is perhaps intentional on Microsoft's part.
Not really. Offices were one of the major early adopters of computers and windows is perfect for them with plethora of features they offered right out of the package.
Windows GUI was groundbreaking, their text processing and excel was a game changer, and windows doesn't allow you to delete your own boot partition with a sudo command so it was pretty idiot proof.
Once windows had the majority of marketshare, it was pretty obvious that whoever was buying PCs (back in the day it was more that a dad got a PC from his office or bought one which was similar), got it with windows.