How to support other authors with impostor syndrome?

I’m not sure if this is the best place to ask this… but I’m not sure where else to go, so here it is:

I slightly know an author through Facebook (we’ve commented on each other’s posts in a mutual group, etc), and she seems to have really bad impostor syndrome and is intending to pull all her books from Amazon because she thinks no one likes them. (I asked for a link to one book to buy it, and it has 56 reviews with an average of 4.1 stars.) I’ve tried to be encouraging when she’s posted about not being able to find readers (and recommended Thomas’s approach of finding a Timothy), and she’s always responded with, “I tried, but no one likes my books and so it’s useless.” She’s also complained of getting very negative beta reader feedback, which I get, but she seems unwilling to accept that the beta readers are either wrong or are giving her information she can use to improve her writing, instead of just despairing.

Anyway, I know this probably isn’t my responsibility because I don’t even know this lady in real life, but it’s bothering me to see her this despairing when her books are actually doing well (from what I can tell). It’s also frustrating to me (as a very solution-oriented person) that she isn’t willing to pick herself up and keep going…. I offered to beta-read if she can’t find any beta-readers who are willing to be supportive, and she did not take me up on that.

I’ve tried to put it out of my mind, but I’m really struggling to do so because I’ve been there as far as the impostor syndrome goes. I also suspect she has anxiety and depression, which I also have… so I guess I kind of feel like I’m seeing myself but without the tough love from my family that’s helped me get through both the impostor syndrome and the mental health things.

All that to say… is there even anything I can do at this point? Again, I’ve tried not to worry about it, and I just find myself hurting for her with nothing I can do about it.