I’m not an expert but i learned about this at university one or two years ago. I’m not entirely sure of what i’m saying though, so take my word carefully and feel free to correct me.

From what i recall -and i think at least in western europe, i don’t know for other places-, before photography, it was quite expensive to get a portrait or a family portrait, mostly because of the time needed to pose. So it was something only nobles or rich bourgeois family could afford.

Then photography was invented. At first, it was mostly an amateur hobby : you had to be a handy(wo)man to get all the components needed, and in first times even to build your own device. There were no schools, no official degree, knowledge only passed from person to person.

So first “professional” photographers (i mean the first one to get paid) were not exactly professionals, most had no previous clients, or anything. Of course, their prices were much low than painters, so increasing number of people came to their shop. But it was for the most part “new” customers, middleclass people or families, would previously could not afford paintings.

So at first, they did not really stole painters’ jobs, they rather extended access to portraits to a new part of population. Now, when it became more popular, the less rich clients of painters tend to switch to photography : it felt modern, it was a kind of trend, and it was cheaper.

At that point, some of the painter’s client disappeared. But there were mostly two situations : big and renowned painters still got jobs, because noble people kind of considered photography a thing for common people. Modest painters, who had client amongst bourgeois, began to lose their jobs. I think that a part of them switched to photography at that point : i also think this is were photo editing began, because they could use their painter/drawer skills to erase or slightly modify the picture when it wasn’t “dry” (don’t know the specifics of photography at that time ^^').

So overall, if you compare like the XVII century and nowadays, of course painters lost their jobs. But from what i (think i) know, transition was pretty smooth, as it let time to painters to continue to paint for upper classes or to convert to photographers.

I pretty much agree with other people, not sure if the comparison with AI is perfect. But at least I think it might show that new techs mostly comes with two effect : replacing previous practices and creating new ones (or at least opening them to new people).