Why would anyone pay 10 dollars for this when the exact same thing is available on Blizzard's site for free.
I could see paying for this if it actually ran on an older system, but the Win7+ requirement for a game this old is quite literally insane.

So, where exactly do you find this free on Blizzards page? A direct link would be helpful.

Free on Blizzard's site? I looked, did not see it free anywhere.

And I think you have GOG backwards when it comes to old games working on newer systems, which is the point of releasing a game on GOG. Not old games working on old systems, which is when you would buy an original version of a game.

Why would anyone buy Diablo for $10? Because it's not available legitimately online anywhere else.

It is an "old product", so free on Blizzard's site IF you have the old CD-key transformed to new digital access key.
Otherwise no, it's not free.

Btw, as D1 is a badly coded mess, AND Blizzard is a dying company, yes, the question has some merrit.
Still, some of the money goes for GoG, and the original version is problematic to run on new systems, so there.

Though I bet soon it'll be fora discount. I'd say w8 4 that.

The original Diablo has no CD key. It relied on checking your CD-ROM drive to see if the disc was inserted.

Well, either way youshould just be into Diablo: Immortal.

Don't you people have mobile?

Not sure where you are making up this info from but Diablo 1 is definitely not available for download anywhere.

Hence why it says "first online copy available" for this download.

There are ISO files available for download on some abandonware sites. Not an official Blizzard download anywhere. However that ISO isn't freely given away, it's a gray area at best, piracy at worst. Also plain old Diablo, no patches, no improved resolution, no local multiplayer.

GoG did a good job putting all the utilities together and even making their own launcher. Given how many hours I spent playing Diablo 1, it's definitely worth the price.

It might have been "a gray area at best", not anymore.
(Though I do consider downloading the abandonware version while owning the disc version perfectly fine. I did, and now I also bought the GOG version.)

As of today Blizzard's site actually states "Diablo is available for purchase at GoG.com" on the Diablo store page.

Just return to the bridge you came from, Troll.
No food for you here.

Abandonware is not legal. It is piracy as games on these websites are illegal copies. As long as copyrights are effective, it is not in public domain. And in some countries it take 70 years after disappearence of the author to fall in public domain. Ask Disney how they keep rights on Mickey.

"legal" is nor universal nor absolute. Hence the word "gray".

Legality depends of your country. But as more and more countries adopt international agreements about copyright, you have more chance to become a pirate by downloading on abandonware websites. But perhaps, you can try north korea... Sorry internet is... limited in this country.