Haha even if I put in more then, I wouldn't have had the conviction to hold them like you did with AMD from the early years till now. I sold off some of my SG stocks during the 07/08 crisis when they recovered and breakeven a little bit! I rmbr you mentioned AMD dropped 50%+ after you bought? That would freak me out already, much less continue to hold it long term.
You should be freaked out if most of your portfolio is in one stock and it goes down 50+%. Statistically most stocks that suffer a 70% drawdown never recover.