“What am I missing?”
I don't think you have done as well as you are bragging about. Stock averages have made no net progress since 1998. So I suppose you are an expert stock picker, you know, you've picked all off the winners, none of the losers like GE, Microsoft, and bank stock, PG, CISCO, Ford, GM, Wal Mart, etc. I could go on and on. I bet you just bought the winners like AAPL and Google.
I am talking cumulative. However, Walmart I do have and have had it since 1995 and it has been doing very well. I also have had McDonald's since the 90's. Harley Davidson as well and Apple since around 2001. And many others. I am not saying that I have never lost money (on paper) but the point is to not panic when things are bad. Just ride the way and buy more when you feel comfortable that it hit bottom or close to it. There is a HUGE possibility that as long as you pick reliable stocks, the companies will still be around come retirement time.