These companies have terrible unit economics and are in precarious financial positions.The last 15 months have been a fantastic time to own stocks. The last 15 years, if we're really being honest. In this most recent run, an artificial intelligence (AI) boom and soaring profits for technology companies have helped the stock market indexes break through to new highs multiple times in 2024.Investors also appear excited to once again place bets on money-losing start-ups. In that way,  the market feels eerily s ...