Not only Bitcoin but yeah Bitcoin is the case study here, every investment shouldn't be started with a borrowed money especially when you don't have another  source to  pay back. if you do have another source, that doesn't mean you should borrow to start, learn to start with the little you have then base on the success yield a borrow scheme could could be planned to meet up at some crucial point.
This could be  aplied in bitcoin, some  dip could brought about it  but still not advisable unless there's an assured means to payback (as mentioned already)