You can also form very strong opinions early in your career and not know when they're now invalid due to changes in tech/industry.

Was getting a quote for a new heat pump and had the guy tell me they were worthless if it got too cold. There have been consumer heat pumps that work down to -15°C with very little efficiency loss for well over a decade at this point. He had just been used to them not being worth it for long enough that he "didn't believe it".