A confident voice with credentials, a big following, or a Bloomberg terminal in the background gets extra credibility for free. In markets the extra credibility is rarely earned, because forecasting skill is weakly related to seniority and almost unrelated to follower count.
The bias also works on yourself. Once you have publicly called a direction, you have become an authority with a reputation to defend, which makes changing your mind expensive. That is where belief-perseverance takes over.
The discipline is to ask for the argument and the track record separately. Anyone can be right. Ask how they would know if they were wrong, and whether their published record includes the losers.
Related: social-proof, survivorship-bias-in-advice