In business, persistence is polite because the alternative is to contact somebody once, and if you don't get what you want, you give up and you curse them and say bad things about them for years to come. Whereas, instead, if you understand that a rejection is nothing personal at all [and] has nothing to do with you; it's just their current situation... Well, then [it's] actually very thoughtful and polite of you to just politely persist.