Why expend so many pleasantries to neighbors who've not given you the time of day until there is money to be made? These people aren't your friends, they don't care about you, they only want to make money off of you.
Don't expend time and mental/emotional energy concerned about these non-friend's feelings and approval.
Don't go and drink/eat up. They serve cheap crap at these gatherings and if you are gentle enough a soul to be concerned about saying "no" nicely then you'll likely be gentle enough a soul to succumb to the "you drank some punch, therefore feeling guilty enough to buy this useless candle/house cleaning/whatever set." (NO judgment --- I was just like this years ago, I totally get it.)
You don't owe them a response. You certainly don't owe them an explanation. And you don't owe them a "thanks" if you do respond -- a simple "no" will suffice. There's no reason to "thank" them for being a consumer sucka annoyance.
Decide to practice being assertive with these people who aren't your friends and only want your money and, as one or two previous posts mention, respond with, "No, I don't like pyramid schemes. Remove me from this distro list."
What is the worst that will happen, they'll stop pretending to like you only when sending their fake friend invites?
I've been down this road and although tough at first, you'll find it is liberating to firmly draw your boundaries and no longer deal with this consumerist, make money off of your "friends" b.s. These so-called neighbors/friends are the perfect place to start your road to ending the "pleaser" mentality. (
http://absoluteconfidence.com/confidence-resources/confidence-articles/people-pleasers-the-price-for-being-too-nice)