thanks, actually in the US you are not entitled to an attorney in civil cases, only criminal casesSomething to keep in mind. While they can sue for any monetary value they want, it has to be proven to be realistic if they actually want to be awarded that damage. If they are going to ask for a million, they have to show that they actually suffered a million dollars in harm/damage, or potentially show the the photographer has sold work for a million dollars and was harmed that way. All of this can be biased however depending on where trial is held (if it goes to that) and the bias of the judge, and how good their attorney is.
I could be wrong bur going to jump out the limb and say the owner paid a flat fee to attorney to send out these letters to whoever they could find. I highly doubt an attorney would take this on contingency (unless the photographer has sold work for a lot of money that can be easily proven to be "harmed"). This is common for a lot of creative industries.
There doesn't have to necessarily merit to file a suit. But also claiming that the website is a "personal" site or that the photo is "nothing special" is not a great defense and a fast track to getting a ruling you won't like. You aren't to judge the merit of whether a creative work has merit, and the judge/attorneys will repeat that. The trial is only to determine if what you engaged in something illegal, and worse off, if you did it knowingly. If you actually did go to court with the responses you posted above in response to others, you may not get a favorable outcome.
Settle, if possible. If you know the artists (probably in the letter), look up if he's an established artists. He could be an emerging artists, and is now doing this to protect work as he becomes more marketable. In this case definitely settle. If they won't accept settling, get a good attorney. If you can't afford one, well as they say, one will be assigned to you. Probably not great. So in that case, go with remorse, apologize and ask the court to show mercy.