The QQQ began its 20-year history shortly before the demise of the dot.com. Since bottoming in October '02, the fund has handily redeemed itself, screeching to new all-time highs.
Performance of the QQQs relative to sector SPDRs or other indexes has been rock-solid going back to January '11.
That said, the fund is highly concentrated in just a few blockbuster names. Empirically, risks proved somewhat higher than the S&P 500. Investors in the QQQs have liquid options access.