It's a complete waste of time and money
Unless you happen to live in one of the very few countries were University is free or very cheap, studying at a University is extremely expensive. We are easily talking about tens of thousands of dollars (or your regional equivalent).
University is also a very unique and extremely important part of your life, if you get to enroll in one. It can be the most important period of life where you learn an actual profession, which you will probably be working on for the rest of your life. Universities are usually the places with the highest education standards and content, which allow you to reach the most prestigious and most useful careers.
Wasting this unique opportunity, and all that enormous amount of money, is one of the stupidest things you could ever do in your life. You should take this opportunity to study something useful, such as one of the STEM fields (Science, Technology, Engineering, Mathematics). These are the fields that have an actual career prospect. Gender studies do not. Gender studies is completely useless in this regard, and have very poor career prospects. You are most likely to end up in a completely unrelated job, and all your years of study and all that money will have gone completely to waste.
(Ironically, gender studies majors often complain how there are so few women in STEM fields. While they themselves chose gender studies over those fields. Think about that for a moment.)
It makes you into a bigoted, angry zealot
This is not something I am saying. This is something that feminists who have enrolled in gender studies at University are saying.
Many of these students were very rational, reasonable and normal before enrolling, and became angry, bigoted and incredibly paranoid afterwards. Gender studies courses is essentially indoctrination and brainwashing. There are quite many testimonies from feminists who say things like "I didn't even know how much sexism, misogyny and racism there is all around me before these courses", and "I started seeing sexism, oppression and racism everywhere", and "every time I went to class, I became angrier and angrier".
And mind you, those are not confessions of ex-feminists who "deconverted" and saw the error in their ways, and are telling their stories as a warning to others. No, those are testimonies of feminists who still think like that and are saying those things as if the were a good thing. That's the level of indoctrination we are talking here.
It makes you paranoid, antisocial, and unhappy
While closely related to the previous, it deserves its own attention.
As mentioned, gender studies classes tend to make students paranoid. People who were completely normal, had normal attitudes and views of society, and were very sociable and nice, become very paranoid and angry. They start seeing demons everywhere, in the form of rampant sexism, oppression, misogyny, racism, and so on. Even minor and completely inconsequential things that are not related in any way, suddenly become symptoms of the deeply-rooted oppression and sexism in our society. You are also very likely to become a racist misandrist who hates white men (even if you are a white man yourself!) You may try to convince yourself that you are not, but you will.
Recently "converted" feminist social justice warriors are extremely antisocial. They can't stop talking about their paranoia, and they are extremely irritating to be around. They will anger and drive away people close to them. They will most likely end up hanging with only likeminded social justice warriors, which ends up forming a cult-like environment.
Social justice also makes people unhappy, even from eg. hobbies that normal people enjoy. For example, numerous feminists have written articles about how they feel guilty, dirty and bad people because they realized that they actually enjoyed eg. a video game which, on second thought, they then found "offensive", or "sexist", or "oppressive", or whatever buzzword. Their feminism kills their own enjoyment, and makes them feel guilty and unhappy.
There is no joy in the life of a modern feminist social justice warrior. There is only anger and unhappiness. Like in that one South Park episode, in their eyes everything becomes excrement, and they can't enjoy anything.
It causes fundamental human rights problems
I have been recently writing blog posts about how universities are becoming the antithesis of academic freedom and free speech (such as here and here). The social justice warriors in many universities are aggressive, and they trample all over the most fundamental principles of freedom, sometimes even breaking the law in the process. We have all kinds of astonishing extremism, all the way from people advocating explicitly ending academic freedom, to people banning white men from attending events or enrolling for leadership positions, harassment of falsely accused people, and amazingly racist comments. We even have feminists attacking other feminists (read the whole story, it's quite telling.)
We are reaching a point where being a white man in a University is not safe anymore. You are treated like a second-class citizen, like a sub-human. You have less rights than everybody else, and if somebody eg. accuses you of being a rapist, your life is pretty much over, no matter how innocent you are. You will be harassed, you will be put into black lists, and even your health and safety may be at risk. Even if you aren't accused of anything, we are going more and more into a direction where you will have less rights than other people, and you will be the subject of insults and defamation, for the sole reason that you happen to have the wrong skin color and gender, and you'll simply have to endure it.
None this nonsense comes from the STEM departments or their students, or from some outside party. No, all of it comes directly from the gender studies departments and their students. They are directly responsible for all of this. It's these departments who are causing the end of academic freedom, and who are producing a generation of sexist, racist bigots.
If you are a good person, please do not enroll in gender studies, or any similar courses. Please remain a good person, for your own sake, and the sake of everybody else. Do not waste your life. Enroll in a STEM field; you'll be much happier and much more productive, and you will be actually helping our society, rather than destroying it.