3 ideas
When a team credits wins to a talisman, players quietly transfer responsibility for outcomes from their own effort to an external charm. That undermines accountability and makes performance brittle, because the team's confidence now depends on the charm being present rather than on its own discipline.
Once people see someone as a source of luck, they value her for what she is thought to cause, not for who she is. Her own agency, feelings and choices are overridden by public demand, and any loss can be blamed on her, so a symbol is at once elevated and made disposable.
Sponsors, cricket boards and media make money from a mascot's supposed powers whether or not those powers are real. Because the belief itself sells products and draws attention, institutions have a financial reason to keep a superstition alive and grow it, even when it harms the individual or the team's discipline.