For startup investors, a company going public is the holy grail. That’s when the relatively small amount of money they invested into a young company turns into (hopefully) big bucks. There are three paths startups can take to going public — initial public offerings (IPOs), direct listings and special purpose acquisition companies (SPACs). Andy Gordon and Vin Narayanan assess the strengths and weaknesses of each one of these paths in this week’s Startup Insider.  …