A stock market in a bubble is dangerous. Being absolutely sure it is—or isn't—a bubble could be worse. That tension runs beneath a stretch of market history that has delivered eye-watering numbers: semiconductor stocks rose more than 38% in April, their best monthly return since February 2000. On April 30, Alphabet gained 10% in a single session.

Alphabet's parent company added more than $421 billion in market value that day, the second-largest one-day gain for any stock on record, per Dow Jones Market Data. Semiconductor stocks, meanwhile, posted a monthly advance rivaling the euphoria of the dot-com era. Investors have been quick to assume they know what comes next after moves like these.

The core problem is confidence masquerading as insight. Whether you're convinced a bubble is inflating or convinced one isn't, conviction itself becomes the risk. These April numbers—semis up 38%, Alphabet adding $421 billion in one session—should give pause to anyone trading on certainty rather than humility.