What is the most difficult part of fix and flipping?

[Troy Springston]

I've been teaching people different techniques of flipping houses and I was curious to see what challenges most new and experienced investors face these days when rehabbing and flipping properties. I want to be able to mentor my students to the best of my abilities and so the more knowledge I can share with them the better off they will be. I truly appreciate your time and answers.

Please answer this question: What is the most difficult part of doing fix-n-flips/rehabbing properties?