You're kidding. Right? Do you really think I haven't looked into these issues over the past 35+ years? CCC pretty much explained it:
If you are careful, you will not "open the door to strangers" or go to the "red light district" - i.e., don't open attachments that you are not expecting from anyone, even folks you know (in case they have been compromised) and don't visit suspect websites.
A computer user's behavior is the main problem. I don't download illegal software, music or adult content. I don't use torrent or P2P software. Keep your nose out of areas of the web where the majority of this stuff lurks, and you're highly unlikely to ever see it.
In all the years I've used DOS, then Windows (and still do), I have never once had any malware land on my computer. Ever.
To get back to the point, though. QT 7.7.6 installed with no problem in Windows 10. However, 7.7.8 won't install, insisting it requires Vista or Win 7.