There are many ordinary or everyday reasons why people won't upgrade:
- They don't know how to do the upgrade. Even if Windows 10 was among Windows Updates people would hesitate. When one buys a PC Windows is there pre-installed.
- Hard Disk is almost full of pictures etc. People don't know how to move pics somewhere else.
- All important passwords will be wiped out during upgrade. Many people live their digital life this way.
- Windows 10 is so much different from Windows 7. Friends don't have Windows 10 and can't help.
- At work Windows 8/8.1/10 is not present. Nobody has ever seen those versions.
- There is plenty of time left until 2020 when one can't receive anymore Windows 7 security updates. One can always install Chrome web browser if Internet Explorer is in danger and go on until 2030!