but is it really that dangerous to do so?
Actually, the answer to that question is an unqualified "no!" -
for today!
Tomorrow, on the other hand, may be a completely different story.
And that's the problem. Nobody knows how long W7 will remain safe to use. There is over 30 million lines of code in Windows 7. "Today", as far as we all know, all the "
known" vulnerabilities have been fix or patched, either my Microsoft or by the anti-malware software industry, so the bad guys cannot exploit them.
But "tomorrow" (or even later on today) a brand new, "zero-day vulnerability" may be discovered. A zero-day vulnerability is a newly discovered flaw that has not been fixed or patched. The danger then becomes if a bad guy learns of that zero-day vulnerability (or discovers it himself - and they are looking!) and then develops and distributes a "zero-day exploit" - malicious software (malware) designed to exploit that vulnerability to compromise your computer, your data, or your (or your kid's
) personal security.
With W10, there are huge teams of "white hat" (the good guys) security experts at Microsoft and throughout the industry actively combing through the Windows code and all the data floating about the Internet looking for flaws in the operating system as well as malicious code seeking to exploit it.
Microsoft no longer has such teams for unsupported operating systems. And more and more security organizations (including the makers of security software) are terminating those activities too. And the bad guys know that the chicken coop is unguarded - or at least has fewer guards and they may be sleeping.
running any unsupported version where that computer is in contact with cyberspace is an eventual accident just waiting to happen.
This is a key point.
And the bigger problem is, if your computer becomes compromised, a top priority of that malware - like any virus (computer or medical) is it will attempt to spread and infect others. So if (or rather when) your W7 computer becomes infected, not only does your computer become a threat to you, your computer then becomes a threat to the rest of us. And that is not cool!
So, you need to upgrade that computer to W10 yesterday. If that hardware is so old it does not support W10, then I recommend migrating to Linux. Otherwise, my best advise is to take it off line. That is, disconnect that computer from any network that has Internet access. And keep it disconnected.
As far as computers not working after upgrading to W10, I'd be lying if I said it never happens. But it really is a very rare problem. The important thing, and ALWAYS an important thing, is to back up any data you don't want to lose before making this (or any) major upgrade.