You can't look at a chart of an index price and simply say "it's down from the peak, I would have lost money". If you do that, you are forgetting that stocks pay dividends, and they aren't included in the index price.
Instead, you should be looking at index tracking fund / ETF prices, which will include the value of dividends (and also account for fees).
Instead, you should be looking at index tracking fund / ETF prices, which will include the value of dividends (and also account for fees).