Do you think its wise to change one's course of career when you are half through it?

I am in a dilemma. I am really interested in neuro-psychology and subjects that really help me understand how brain works and how it results in certain behavioral dispositions and how they can be re-programmed for the betterment of humanity. At the same time, I don’t want to be a low earner, I am expecting to have a fulfilling salary ( not too much but yes, should be good enough). What I am currently into is a masters in remote sensing and GIS systems which does not particularly interest me, I am working on urban spatial growth prediction modeling and I feel that I have entered a wrong place, I am already midway into the course but I am quite apprehensive about its future and whether I will spend the rest of my life repenting. I am not able to focus well and this causing me great distress and unhappiness. I am too sad these days as I am not really understanding where my life is heading. I feel so low when I look at people who are so enthusiastic about their life and career when they say that they were the controllers of their life. Well, of course, nobody forced me to take up this particular study but one of my guardians suggested it to me and I took it , as even I was not aware as to what I really wanted. Now, it feels like life is going terribly wrong and I feel completely wasted. I have terrible mood swings. And I really don’t know who to seek who can help me cure this.
Any comments shall be appreciated. Thanks