I suspect that a lot of the 1-star reviews are due to poor marketing on Netflix's part, which is misleading, but nevertheless, this movie was a better than I was expecting it to be. If you're looking for a movie where the bad guys will get their just deserts, this may not be the right movie for you.
I'm really surprised at the number of reviews I see on here that say that the movie is unrealistic and that it tries to frame Marla as unsympathetic. "I Care a Lot" is a funny, mostly decent satire of the rise of feminist capitalism, aka the "girlboss", touted by female CEOs and presidents who claim to have progressive visions for their businesses, but make money in unethical and exploitative ways.
The movie does a pretty good job at showing how Marla's entirely woman-run guardianship company uses the veneer of female empowerment and sticking it to men to rob seniors of their money. The criticism that the movie is unrealistic falls flat when the movie is a satire. Satire reflects truths in an exaggerated way for a comedic and revealing effect. While it's unlikely that the doctor, judge, and retirement home staff would all be so malicious or incompetent to let Marla get away with everything (and get in on it too), it reflects that the legal and medical systems in place don't do enough to protect seniors, and at the worst, sees older people as a group to exploit. At a larger scale, it shows how people at the top of the economic food chain can get away with almost any abhorrent thing, and our institutions will do little to stop them.
However, my main criticism of the movie is that the second act drags on for too long and could have been cut down. At the worst, a part of the second act which seeks to humanize Marla's character almost undermines all of the efforts to set her up as an unsympathetic character, but the last 15-20 minutes of the film end up saving it because it goes back to its original message. Powerful people and entities will even collaborate with rivals and enemies for the sake of maintaining and expanding their power.