The word is badly chosen and causes more losses than almost any other term in technical analysis. An rsi above 70 does not mean too many people have bought; it means recent gains have outweighed recent losses by a wide margin.
In a strong trend, overbought is the normal state. RSI can hold above 70 for weeks, and the strongest stocks in a market spend most of their advance there. Selling every overbought reading means systematically selling strength.
The defensible uses are narrow: fading extremes inside an established trading-range, or noting that an oscillator failed to reach overbought on a new high, which is a divergence. Outside those contexts, treat the reading as a description of speed, not a signal.
Related: oversold, oscillator, rsi, rsi-range-shift, divergence