Can someone explain to me the whole testing early thing?

Not trying to troll but I'm just not understanding why we see a lot people struggling to make out faint lines because of testing really early. Why not wait? Is it just impatience? I can barely see lines in some of these pictures and also I am reading about chemical pregnancies that seem frequently corresponding with faint lines in early testing. I don't get the reliance on the uncertainty of early testing. Would love to understand rationale!