Primarily those who need SBD or STEEM fast for the use of upvoting bots. Say you have a great post you want to post, but you have a small account with little or no SBD coming in. Then you can borrow SBD, spend it on upvoting bots and then probably, if you are clever and use Steembottracker, you can pay back with interest PLUS make some money. Think someone in Africa, who can borrow 1-5 SBD from me (that is a lot of money for them)

Other possibilites is someone who just need some fast cash for whatever that is none of my business.