Captchas dehumanise you as they are trying to find if you are human. One can always find crooked writing ,if it has the faintest resemblance to letters but they are like the Muni Ashtavakra who has eight crooks in his body. It takes quite many efforts to unravel their identity.
The trouble is that the page does not refresh at each change, if the earlier effort is not successful. The captcha is hell-bent on proving you are not human. So you give up and forget about registering for a new website. Surely that is not a human thing to do.