I'm wondering if therapy even works for real problems.
It's not known for that, no. The entire premise of psychotherapy is that the biggest problem in your life is you. If only you thought or behaved differently, the world that once seemed hostile and joyless would become wonderful, and your life would feel worth living. All you need is a good therapist to tell you all the ways in which you are doing everything wrong.
Seriously, how charmed a life do you have to lead for your biggest problem to be your lack of self-actualization? If that's your worst nightmare, then you're probably not one of the three billion people who live on less than $2.50 USD a day. Your neighborhood doesn't get shot up by gangs on the regular. Your local religious majority doesn't insist that people like you should be denied basic civil rights. You don't live with someone who causes you to fear for your life. In short, you're not most people, and more importantly you don't remotely have the same background as your average therapist.*
I'm LGBT myself, and more and more I've been hearing from people like me that they are feeling unsafe in the area where I live. As long ago as January of 2020 I was talking with queer friends and relatives about whether or not we should try to get out of the country entirely, and things have palpably worsened since then.
During a psyche hospital stay in August of 2020, I had a social worker call a cishet relative of mine to check out whether several of my anxieties were "realistic." My normie fam of course said they were not. Meanwhile, every serious conversation I was having with queer people (other less-loved groups too) referenced the terror they were living in. A friend of mine was nearly run over by a car at a protest. The guy next to him had his leg crushed under a tire. The driver was either homicidal or so brain dead he couldn't tell he was accelerating straight at a group of human beings. This shit is not a joke.
But to answer your question once again, being disbelieved and gaslit by therapists is perfectly normal if you have serious, real-world problems.
*I'm not suggesting that therapists somehow have no personal problems. A lot of them are real pieces of work. Rather, I'm saying that as a group, they have comparatively few societal problems. At the very least, nothing major got in the way of them graduating from a college prep high school program, then a four year undergraduate degree, then a two year master's program. That is really hard to do if you're living in your car and eating out of a trash can.