My cousin who does IT for a bank said never to use the same email for banking and shopping, I ignored him for 2 yrs | Digital Privacy Dilemmas - Opinions Matter
Kept my bank email the same for 6 years and nothing bad happened. The real risk isn't the email itself, it's weak passwords and reusing them across sites. If a shopping site gets hacked and you used the same password there as your bank, that's how they get in, not because the email matched. Most banks also have two factor now which kills 99% of that worry. Your cousin's advice sounds safe but it's more about locking the front door while leaving the back open. Use a password manager and skip the extra email juggling.