Who are these "majority of unicorns" that everyone casually passes around? Yes, there were some journalistically well covered flame-outs, but is there a trend o

Who are these "majority of unicorns" that everyone casually passes around? Yes, there were some journalistically well covered flame-outs, but is there a trend of companies worth more than $1B flaming out? Otherwise, companies without a promising business model flaming out is definitely a good thing.