If you invested in XLK (State Street Technology Select Sector SPDR ETF) In March of 2000 (just before the .com bust), you would have underperfomred SPY (S&P 500) until June 2026. As of today, the spread between the two is just over 1%, with good reason to believe that we are in another tech bubble.
https://www.etftimemachine.com/en/compare/XLK-vs-SPY?start=2...
Had you invested in XLK when it opened in 1998, then following the .com crash, it would take until early 2020 to return to parity to the S&P 500.