Identifying Emotional Bias in Investment Decisions

Sarah is a seasoned investor who recently experienced substantial gains in her technology stocks during a market uptrend. Feeling confident about her investment acumen, she decides to increase her concentration in technology stocks, believing that past performance guarantees future results. Meanwhile, her friend John advises her to diversify her portfolio to mitigate risks, especially since the tech sector is notoriously volatile.

This scenario showcases how Sarah's emotional attachment to her gains may be leading her to overlook key investment principles. The tendency to overestimate abilities and forecast future success based on recent experiences is linked to emotional biases.

Which of the following emotional biases best describes Sarah's decision-making process in this investment scenario?