If it were me, I'd be furious
If I found my work had been used to train a statistical model by people whose specific intent -and let us not pretend they have any other- is to cause me to lose income, I think it would be quite fair that I be angry about that.
The problem of Copyright is in part that it's not exactly designed for this, but how could it be? This type of tool hasn't existed for long enough to undergo serious legal evaluation and even the people training the models don't seem to have a clear understanding of how it works, so we end up in something of a square peg round hole scenario.
In this kind of situation, I think a fair law would lean towards protecting the people creating art. It is one of the most human activities, one of the few things we have records of going back to the very dawn of our existence. The idea that this should be dispensed with, replaced by statistical averages ... isn't there something wrong with that? Isn't it a little sickening that companies like this believe that hurting artists is a business model worthy of pursuit, let alone the investors and sycophants who support them?
The other thing I don't really get is where the profit comes from. I know a good number of artists and I wouldn't say any of them are exactly rolling in it. Mostly they're living hand to mouth and often having to take up other work because the art doesn't pay the rent. If Midjourney or whoever else manages to take every bit of income that they have, they're still not going to make very much money compared with most other industries.