This definitely happened to me when I was pursuing an Associates in Arts in Digital Animation & 3D Design in Brookdale Community College. There were moments when I was just halfway complete with my degree when I asked myself "What am I even doing here?" This started happening because as I was actually doing the coursework, I found that I did not like it. There might be a chance that you will not like the coursework you do in your major, so it is important to keep that in mind.
I could only make the change to a different major because I figured that I would not like this career in video game design, especially since I already had different interests such as the story-telling side of this field that outweighed everything else. I was willing to study the inner workings, such as software like Maya, if it meant exploring the story-telling side; however, that started to wane. Another component to that change was the reality that the games that inspired me to pursue this field were no longer interesting to me and I stopped playing them. What to take from this is that the very sources of your inspiration for pursuing your major might no longer interest you and would not last you.
So I decided to pursue a semester as a Programming major. As it turned out, it did not stimulate me. In fact, it was really difficult and I could remember already feeling sick near the end of the semester. The stress of completing all of my assignments and studying to pass the tests took its toll on me and made me so violently ill, I ultimately decided to change my major once the next semester started.
I figured that becoming a Programming major would sustain me since Programming is one of the highest paid professions. However, the world is an unpredictable place and there is not always a guarantee that you will make a lot of money that sustains you simply because of the major you chose. This was especially true with famous YouTuber Matthew Santoro who was originally an accounting major. Your major might not give you long-term happiness or even job security. Making money should only be one other reason to pursue your major.
A point was made in the Roadtrip Nation book titled "Roadmap," where if you are working a job you do not like, you spend eight hours a day, five days a week, and 52 weeks a year, therefore you are merely spending 90,000 hours of an entire year working for a job you do not want. So you should take into consideration the amount of time you would put into your major because you do not want that time to feel wasted, for it is just as important as the money that is involved, which is (of course) where we have the phrase "Time is money."
I ultimately decided to become a History major, because I was fascinated by how people function at a historical level. Not only that but there were famous authors such as Steven Erikson and Greg Keyes who have studied history and other related liberal arts fields. I figured that I wanted to go down the same path they did, considering how literature and history were the only fields that occupied my mind while I was a Digital Animation & 3D Design major and a Programming major.
Then when I transferred to Monmouth University to pursue my Bachelor's Degree, I changed my major one final time. I entered as an English major. The reason why I did not go in as a History major (though I did pursue an undergraduate minor in it), was because I was convinced of how multifaceted the English degree was at an English major seminar. I even highlighted those grievances commonly made against English majors, which is that "You'll never find a real job in it." This change could have only been made possible by the reality that I wanted a major that would encompass my everyday life, and as such, the English major provided incredibly helpful life skills, such as research and developing a well-informed opinion.
If you want to pursue a major that is sustainable to you, not just monetarily but creatively and emotionally, then it is ultimately your choice as to what field of study you should pursue. If you are just about to complete high school and look forward to tertiary education, then I would highly suggest making some serious decisions about what you should major in. You do not have all the time in the world, so it would be best that it be used wisely.