The index has become a bubble in of itself. It's also not as diversified as you would think when Microsoft makes up 5-6% of the S&P and over 10% of Nasdaq.
So then purchase and overweight small and mid-caps and international indexes if you think that SPY is top heavy. You don't need to deviate from index investing just because a part of the index is outperforming the rest. Choose an allocation, stick to it, rebalance when you hit some threshold.
You don't have to stick to the S&P index. There are others that follow tech, or commodities, or the Canadian stock market, green energy or what have you. You can diversify yourself.
