For a start, dismissing someone as a "doomer" because they believe bad things could happen is just unproductive. I didn't see this behaviour so much in the past, but today I see it everywhere. Recently I've noticed a trend where whenever people raise concerns about issues like climate change or public debt there's always someone laughing dismissively, "haha, what a doomer. We've heard it all before bro!"
If you're someone who does this, please stop. Try being less intellectually arrogant and make actual counter arguments instead.
Secondly, whether you personally believe AI will be good or bad for humanity this notion that because something didn't happen in the past it won't happen in the future is obviously not a logically sound position to hold...
The field of AI prior to the ~2010s was in a very different place than it is today. For decades neural networks were extremely limited in their capabilities. What we've been able to do with deep neural networks over the several years has progressed rapidly and has finally allowed us to build useful commercial applications such as AI voice assistances, chat bots, and self driving vehicles.
It's an observable reality that things are different today. We're no longer in a time where AI systems might hypothetically do things humans once did – we're now starting to see this play out in real time, perhaps exponentially.
Some will argue this has always been the trend with technological progress. Notably the industrial revolution allowed us to replace many repetitive manual labour jobs with machines. But thankfully humans weren't great at lifting heavy objects and precise repetitive motion anyway. I think one could argue that the industrial revolution actually freed up humans to do what they excel at, thinking. I'd argue it wasn't the machines that drove the growth of the industrial revolution but a mass unshackling of human creativity that hadn't occurred since the development of agriculture.
That's why this time this could be different. Machines are stronger, faster and cheaper than human labourers. The only thing we have is our intelligence... Obviously we humans are extremely adaptable and dynamic, but not infinitely so.