Ned Ryerson's main purpose in this movie is to test Phil Connors' level of tolerance for annoying people… incredibly annoying people.
At the beginning of the movie, Phil has very little patience for people and he meets his match in Ned, who runs up to him on the street and gives him a passionate speech about how the two of them go way back. He concludes by doing the most annoying thing he could do—sell Phil life insurance:
NED: Do you have life insurance? You could always use a little more. Am I right or am I right or am I right? Right?
PHIL: I would love to stand here and talk to you, but I'm not going to.
By the end of the movie, Phil has decided to treat Ned with kindness even though he still finds the guy annoying. As Ned explains to Rita,
NED: He [Phil] comes to me and buys whole life, term, uniflex, fire, theft, auto, dental, health, with the optional death and dismemberment plan, water damage. This is the best day of my life.
Phil might not think the world of Ned, but he's still willing to make the guy feel good in any way he can. And if Phil can be nice to a dude like Ned, he can be nice to anyone.