Oh man. That's astounding! D: From my own vantage-point of a measly (but seriously and deeply appreciated!) $50 a month on Patreon, that looks mind-boggling! Well done her!
As some people have said, it's a bit of a legal grey zone doing fanart for money, but if she's got licenses for it, I suppose it's alright. Her stuff is not personally my taste (I don't like that kind of photo-realism - I find more abstracted/cartoony styles more appealing) but I'm glad to see someone making it big like that!
@UzukiCheverie Here's the thing, though. While it might seem a bit silly to say that of someone making half a million a year off her art - she, and people like her (those who are "internet famous", or whatever) have bills to pay. Would you criticise a plumber for treating his customers as sources of income? Or someone delivering pizzas? Yes, being nice to people on the internet is a big part of her business, but it's not strange that she would have more interest in her paying fans than in her non-paying ones - the paying fans are the ones putting food on her table and a roof over her head.
As long as she's not actively trash-talking her non-paying fans, I don't really think we have any room to criticise her. Like you said, she's bound to have thousands of fans, and there's just no earthly way to keep in touch with them all - so it's only natural she prioitises the ones who are paying her bills.
All this frantic activity on social media makes us feel - wrongly - that we have some sort of proprietary right to be personally acquainted with everyone, even super-busy famous people, and that just isn't true. You only have a right to know the things about Sakimi-chan that Sakimi-chan chooses to share with you. And if she's holding some things back, then she's got all the right in the world to do so. "Ignoring" non-paying fans is not necessarily a reflection on her having "forgotten her roots" - it's probably just her being extremely busy and not having the time.