My understanding of the research is that, compared to a placebo, antidepressants help as much as 20% more of the population (20% -> 40%), and the broader scope of drugs can help around 30% to 40%[1] of people. People routinely feel suicidal, take SSRIs, and later stop feeling suicidal.

[1] https://youtu.be/NOAgplgTxfc?t=2294