Should I switch labs, three years in?
Almost all grad students feel under-appreciated by their mentors at some point.

Your adviser sounds like a top notch A-hole. Unfortunately, to be a successful researcher in academia, most institutions look at (in order): the quantity of grant money being generated, the quantity/quality of research publications, and how many PhD students you generate. In other words, most research faculty consider the needs of their PhD students last.
Therefore almost all grad students feel under-appreciated by their mentors at some point. What keeps most grad students going through the 'tough times' is they enjoy the subject-matter they decided to go to grad school in. What I recommend is:


Have you began work on a thesis paper? If not, I would consider the door wide open to a change of departments / research groups. Especially if you don't have a passion for your work. Any future career path is going to be influenced heavily by your choice of research; why go down a path you know you don't want to pursue?
Finding a major professor who can simultaneously be your academic mentor and best pal is hard. You are going to need to pick a field of research you have a passion for if you plan on making it to the end. If finding someone you get along with is important to you, the easiest way to tell is to rely heavily on the next bullet:
When looking into another graduate course of study / department / laboratory, ask the current graduate students. This is going to be by far the most useful input: if at all possible, ask them about their relationship with faculty. Ask them about their workload. Ask them if they publish. Ask them if they feel supported. Ask them how long it takes.