Originally he was a well liked, well respected autuer game designer from back in the days when that was still a thing. He made games like Populous, and people thought he was pretty cool.

Around the time of Black and White, the cracks started to show. He had bought into his own hype, and had a real tendency to over promise and under deliver. But, even though it didn't exactly match up to some of his more grandiose descriptions, Black & White was still a very good game, so people didn't mind.

Fable was where things really went off the rails. The thing is, Fable was a very good game, a fun but largely quite contained RPG, feeling more like a western take on a Zelda game than anything (as in the N64 Zelda games).

But it was not the game that Molyneux promised. Not even slightly. The game he described was one that would have nearly photo realistic graphics, and a vast open world where you could literally see a distant mountain peak and set off to climb it. A world where you could kill a man in a duel, and his son would grow up dedicating their life to one day hunting you down and killing you. A world where you could conquer whole nations with armies of darkness at your command.

Think Skyrim crossed with Mount & Blade crossed with Crusader Kings crossed with Star Citizen. Now imagine that game releasing at the same time as Morrowind.

So by this point people were starting to understand that Molyneux was fundamentally incapable of a) reigning in his imagination, and b) operating in the modern world of game development.

And then we got to Curiosity. If you don't know, it was a mobile game where all you did was tap on a big cube made of layers of little cubes. Every time you tapped on a little cube it got destroyed, and everyone was working together on this, so each cube was destroyed for everyone. The goal was to destroy all the layers and reveal the centre, and whoever destroyed the last layer would win a prize. Kind of dumb, very simple. But Molyneux, Molyneux hyped this to the heavens. This wasn't just a "game", oh no, this was a grand social experiment the likes of which the world had never seen before, and the winner would recieve something "truly life changing." Molyneux hammered that point a lot. "Life changing."

What they recieved was that a character would be named after them in Godus, the Kickstarter game Molyneux was making. Oh, and they'd get "a portion" of the revenue from the game (it was never publicly stated how big that portion would be).

That was back in 2013. Ten years later Godus is still in early access, backers are clamouring for refunds after basically none of the Kickstarter promises were met, and the winner of Curiosity has not been contacted by the company since 2016.

He has never seen a cent of the money he was promised.

So, yeah, that's the problem with Molyneux.

Why all the hate towards this guy?

As time went on, he developed a reputation for big promises and hype and underdelivering - viewed by some as straight up lying. He arguably killed the Fable brand. He presented a tech demo for the launch of the Kinect that was thought to be a real game, that was mostly smoke and mirrors. Following Fable 3's poor reception, he makes his own company and hypes up "Curiosity", essentially a bad clicker game with a promised prize to the person who gets the final click. The tech was bad, and the "prize" was supposedly a share of the revenue from their following project Godus. That project was not good (which was only expected to be at all due to his penchant for inflating expectations), and the cherry on top was that the person who won the prize for the aforementioned Curiosity game never received a dime.

After that, people stopped caring.

He exaggerates or straight up lies about the games he has made. Despite some of them being very good, they still under delivered on many outrageous claims Moleneux has made.

Like with Fable, he once said shit ranging from that you'd be able to do shit like carve your name in a tree and watch it grow and the scar evolve over time and even seemingly minor things like fighting a dragon as a boss which didn't come to fruition.

Even if you know nothing about the past of this guy, the fact that he made a blockchain-based business sim should tell you all you need in order to form an opinion.

I didn't play those but I remember spending a lot of time on Populous. That one was quite good.