Warren Buffett once said, “You’ve got to be prepared when you buy a stock to have it go down 50% or more and be comfortable with it, as long as you’re comfortable with the holding.” That philosophy applies directly to growth stocks operating in nascent markets with the potential to expand dramatically over the coming decades. Three companies stand out as compelling long-term holdings despite current volatility: Joby Aviation (NYSE: JOBY), AST Sp…