Why Is Vega a Critical Greek for Long-Term Options Strategies?

Vega measures the sensitivity of an option's price to a 1% change in the underlying asset's implied volatility. For long-term options, the time to expiration is significant, meaning the uncertainty (implied volatility) over that period is a major component of the premium.

Vega is critical because it quantifies the risk associated with changes in market expectations of future volatility.