The reason people are on older operating systems isn't because they don't like change - same thing happens to companies/professionals who use Linux/MacOS, it's more complex (and expensive) than just "let's update it" in the real world with a lot of cost/benefit analysis required- these people aren't just using Facetime and browsing Safari, companies can become bankrupt from a failed IT project.
It has no correlation to USB-C again.
Most companies/professionals are on Windows 10, because they rely on security patches, Microsoft support, etc. Their IT guys do the updating and after 2 years, yeah, they had time to do it. But companies/professionals are a small percentage of computer users. Vast majority of users are home users who had two years to update to a newer, more secure, more stable system. But they had to do it themselves, and wait for an hour for the thing to complete, and then get the new drivers, and it's a hassle - you know?
So, no, the reason why people are on Windows 7 is because they hate new stuff on computers, not because they are professionals.
People still using Windows 7 are using it because they don't care about updating or just won't bother with the 'hassle'. And it that's 50% of users. People just don't care, and they don't like new tech, and they don't really like computers but have to use them.
I read somewhere that a significan percentage of Mac users still didn't get used to the right click on the mouse. The reason: "it's confusing - they are used to the old way of using one-button mice". 3D Touch? Force Touch? Good luck with that.
But at the same time, people expect computers to do more, faster and better. So, people will whine that they have to get new cables to charge the iPhone on that Mac, but AT THE SAME TIME, they will be angry that the charger they have in the hotel room is not usable on their phone. And that they cannot carry just one charger with them, but need 3. And they will complain how they have a bunch of cables sticking out their computers.
"Apple - where's the innovation!? It's 2017 and I still have a bunch of different cables sticking out of my Mac. If Steve was here, he'd do something! Can't I have just one cable? Invent something!"
"Apple - it's 2017 and I have to carry THREE chargers on my trip!? Invent something!"
But when Apple comes with the solution, everyone is "but, but, it's too soon! And I have all these old cables.... and can't we have both? (even though we all know that will just prolong the transitional period that is, actually, worst of all)"
Just get the new cables, man.