I run almost nothing but mechanical HDDs for my rigs - both retro ones and my daily drivers (no Windows 10 here, so it's not a big deal.) No data loss in 20 years... though I did have one WD 800JD fail on me about 5-6 years ago... and one of the same to be failing soon. Also had a 20 GB IBM Travelstar corrupt its MFT badly in my previous personal laptop. But I tend to keep backups of my important stuff, so nothing got affected. And the IBM HDD was still able to recover the lost files after a long disk checkup session... well, sort of - the files got recovered, but not their names or extensions. 🤣 Ah well, format and start over. I had all my data backed up anyways. FWIW, that drive is still usable. I just don't trust it for a personal "main PC" (laptop) use anymore... which is fine anyways, because the laptop it was in is a Pentium 3, and a bit hard to use for modern everyday stuff, to say the least.
Yeah, mechanical HDDs can fail. But they are not that terrible - not all of them anyways. There are just certain ones to avoid and others that are OK.
My personal preference is for the Seagate Barracuda ATA III, IV, V and 7200.7 series as these have been the most reliable for me... along with Samsung Spinpoints from the same era/years.
Anyways, the fact that both your WD and you Seagate displayed got flagged as bad by BIOS suggests you might have a bad IDE cable on your hands. Check and/or swap it. Also, if that Seagate was mine, I'd put it into an XP machine and read its SMART from a 3rd party tool, as Archer57 suggested. I typically use either HDtune or CrystalDisk. And if I want just a quick check on the SMART, I also have a very small tool called DiskCheckup. It's tiny and takes no time to load (compared to HDTune and CrystalDisk sometimes) so is very fast to check SMART status on HDD.
Do that and see what you get for the Seagate. If it's not making any weird noises, it might be just fine.
Oh, and regards to the monitor thing/question... I think Matchstick answered it pretty well. VGA is indeed a protected circuit, and even static discharge shouldn't be able to kill it, unless the static discharge is of really really high energy type. That's because there are diodes on both ends of the VGA circuit that shunt any voltage below -0.7 to ground or above 5.7V to to the 5V supply. If the energy pulse is small enough, nothing bad will happen. But if the pulse is large enough to literally blow up a diode junction, then that's when you'll see it / smell it when you try to power on the device.