why would someone pay for this when they have access for free in a supposedly less buggier interface?
Because people just don't know it exists? ChatGPT is a open box. ChatGPT wrappers are real apps.
A less buggy interface for some is unintuitive or too generic for others.
Why would someone pay for dropbox when they already build such a system themselves quite trivially by getting an FTP account, mounting it locally with curlftpfs, and then using SVN or CVS on the mounted filesystem?