Arrogance affects the brand

The image of a brand can be affected by the action of the employees in their capacity of work, when dealing with external service providers, even if they have no relation to marketing or promotion.

Sincerity,humility and respecting others, is not only applicable to marketing executives or promoters - but from everyone in the company.

E.g. if a staff representing the company, treats a vendor badly by disrespecting him and making unreasonable demands, the vendor who may also be potential consumers of the brand's product, may not want to even see the brand in shops, because he doesn't want to be reminded of the bad experience with the employee(s) from that brand company. He may even tell his friends and family about it.

However, it should not just be about the brand. It should be about branding ourselves, with sincerity, humility and respecting others. Even if you cannot expect any returns from others.
For a Muslim, it's simpler.. we know (or at least most.. or some of us know) that God sees our every act and word. God consciousness should be enough to lead the person to being humble.

The opposite of humility is arrogance. It's never good.

And no, confidence does not equal arrogance.