Snapchat's steep competition, Facebook, "scares the heck" out of NYU finance professor Aswath Damodaran, he told CNBC's "Fast Money: Halftime Report" on Tuesday. Snap is vying to price its public offering in a range of $17 to $18 per share, putting the public offering above its range and value the company at $25 billion, sources told CNBC on Tuesday....