One argument I've heard from the more ancap types is that these things are okay because intellectual property is a scam the stifles innovation. Let's take that at face value.

Another concept that ancaps often support is time-preference behavior. In a nutshell, high time preference behavior is rewarded by immediate consequences (say, stealing the item gets it in your hands immediately for free), and low time preference behavior rewards long-term consequences (buying the item costs money, but you don't go to jail or contribute to the closing of the business). They argue that societies that primarily operate on low time preference behavior are more prosperous than those that operate on high time preference behavior.

I would argue that the use of AI image generators in particular is short time preference behavior. Sure, you get the picture very fast and for very little money, but the widespread use of AI will discourage more and more people from either becoming or remaining artists. One funny thing AI researchers have found is that AI image gens can't be trained on AI images or else they'll produce objectively useless garage. So taking this to its logical conclusion, the society that relies on AI for all its images will eventually run out of human artists and thus be unable to produce any new art. AI fans are taking the short-term cost savings without considering the long term consequences of eliminating an entire industry.