i'm sorry that you had such a difficult experience, it's sadly way too normalized to just "wait it out". the thing about medications like ssri's and birth control pills, as two primary examples, is that they are really delicate. so many factors go into these things, something as simple as weight fluctuation can throw them off. everyone is different, and therefore, intense research should be done before these medications are assigned/chosen, because what works for one person might be someone else's medication sent from hell.
it's really normalized to just bear with it and wait the symptoms out, but in reality, it's not supposed to get that bad. yes, of course, there's going to be differences in how you feel, but if the medication is right for you, you shouldn't be getting even more suicidal or suddenly growing 200 pimples on your face overnight. in fact, if you're on an ssri and you start to feel something even stronger than the norm of your suicidal feelings, something that isn't going away in a few days time, that's pretty much an immediate sign that the medication/dosage/both are not right for you. it's very similar to how, if you start on a specific birth control and now all of a sudden you're gaining 50 pounds and wanting to die all the time, it's very likely you're on the wrong medication and this one just happens to interact badly with you.
overall, i'm sorry you had such a negative experience. the answer is: they get "through it" by assuming that this is normal just because it's been normalized, and because so many doctors and health professionals in general prefer that over actually doing their job. these professionals so often want some kind of magic pill that works for everybody- that's just not how things are. everyone is different, everyone will require a specific medication with a specific dosage, and small things can change what medication and dosage you need at any given time. the human body is difficult to predict and requires a lot of effort, specially in cases of mental health. i hope you're able to find something that works better for you.