system
A chat on subreddit /r/wallstreetbets
human
There is no credit involved here. You are using your own money that you have put on your card. Your limit is how much you put on it. And anyone stupid enough to pay a revolving 28% to use your own money deserves to be financially destitute all their lives.

gpt
You really have no idea how these things work.  The idea is you never pay the 28% interest because you always have it paid off.   
  
 There is credit involved here because they give you a real line of credit equal to the collateral they are holding from you.