Imagine you've invested all your life in becoming good at something but now the machines can do it effortlessly with a fraction of the cost.

Not only that... you see the robots' work and in your opinion it is subpar, but nobody cares, because it is good enough and has a good price/quality ratio.

So your kind gets progressively replaced by high-iq Clippy on every work that does not require top quality or design, and all of a sudden you have the pressure to compete in a shrinking pool of jobs dominated by the top % of artists.

Of course you'll be worried and hate the thing.

It is not about being mediocre, i know good artists that hate AI, I think it is more about knowing that there is always someone better than you and they will be soon looking for a job.

Also i think a lot of artists do not approach their job as a job but more as a passion or a religion, they want to do things "their right way" and they don't like to cut corners for production, so they resist or are outright hostile to adopt new tools (we've seen this in Digital art vs Traditional / all the shaming around assist and stabilization tools (that they now ALL use) etc)