There’s more than glyphosate in roundup. Also if glyphosate increased the risk of cancer, we would see cancer increase when it started to get widely used. Cancer rates except for skin cancer keep falling.
Sure. Anything's possible. This is a fully generalizable argument. Maybe you, personally, cause 10% of the world's cancer, but other factors have caused an overall falling cancer rate, but when you, personally, die or turn off your magical cancer-causing powers, rates will fall even further.