Most people I know have given up on PCs and use their cell phone for everything. Not me though. Windows 7 still works.
Yes, Windows 7 still works. But even assuming you have a good firewall solution (hopefully hardware based), you could be more vulnerable to hackers because they’ve had a long time to compile a list of vulnerabilities and AUTOMATE attacks against your PC.
A lot of security seems to revolve around security just by making changes; kind of similar to security by obscurity. (i.e. A moving target can be harder to hit than one standing still...which is why people still are forced to change passwords...but it’s another flawed approach.)
So it depends on your needs, including level of security needs - personal use (and there are different levels within that) versus business needs (and there are different levels within that too). Guarding a high value target requires a higher level of protection than guarding something of little value that can easily be rebuilt.