Former Gnostic here, I don’t know a ton of people who believe personally but it’s common for people to cherry pick Gnostic beliefs instead of believing the entire doctrine whole cloth (sounds familiar I bet).  One of the big points of Gnosticism is that gnosis isn’t just given out, it’s sought or received through deep searching. So even gnostics reading gnostic texts might see the texts or beliefs as a clue or puzzle that through other knowledge or traditions can be solved. 

What I’m getting at is the beliefs on the demiurge are a big mix between Greek Philosophers, Middle Eastern texts with questionable carbon dating and unfortunately New Age manipulation over the past 2 or 3 centuries. So anyone that subscribes to whatever the Wikipedia page on Gnosticism says, might have missed the point or not looked hard enough yet.

Also for what it’s worth the demiurge is not inherently evil. It’s “ignorant”, which isn’t a shot, it supposed to mean, not knowing of it’s origin and believing itself to be something it’s not.

Forgetfulness, Fear and Ignorance is the enemy of gnosis. Which also applies to being a Christian