Does chemotherapy kill more patients than it saves? And...

(I have two questions)

I just noticed that for every cancer patient that I heard who undergoes chemotherapy has a lesser chance to survive it, and I noticed that their pain just keeps on coming back… it’s like chemo makes the cancer more malignant, thus making the patient suffer more. Does it really help them or it just makes it worse?

And do you think that they’ve already made a cure for cancer? Because at the back of my mind, I think they have and they just don’t want to release the cure because it would affect a lot of things in the cancer industry. Do you think it’s possible that they’ve made it?

I’m just a little curious. I don’t know a lot about it, I may be talking nonsense (I’m not a smart person). Please educate me on this. (And please don’t insult me for sounding stupid, I’m just trying to learn)