Is the guy who prepared and served the food a part of the foodie group? Or was he hired to cook and serve? If he is a member of the group, I don't think he should be tipped. I don't think he should be looking to turn a profit and make money off of his friends. And a bottle of wine per person? I find that to be excessive and it makes him seem like he's trying to line his pockets AND his wine cellar.
He is not just a member of the meetup group. He owns it. It sounds to me that he wants to have a wine and foodie group and to attract people who enjoy wine with a fine meal.
There are many owners of meetups who charge a fee to be a member or to go to an event. The reason is to offset the $150 annual fee for the MU group and to encourage people not to be flaky with their rsvps. If this guy is opening his home, cooking a gourmet meal and say, 10 people attend, I don't think $35 is unreasonable at all to charge. That most likely includes appetizers, main and dessert. When I do major meals it takes me a great deal of time to shop and prepare. Then cleanup after.
At our wino events, everyone brings a bottle of wine and they are on the table for everyone to try. There is lots, I mean LOTS of food. I don't charge gratuity, but I never had to charge anyone either b/c I have a very strict RSVP policy that people respect. My group is a bit different - it is more intimate - usually about 16 ppl and there is always a waiting list for each event. They are held in member's homes and the host determines how many they can accommodate.
Other meetups, like the wine group my friend runs, is a bit more ...hmmmm... superficial? The people there are not necessarily interested in making friends, per se, but they enjoy going out and trying new wine. She charges $5 to attend each event (paid at the yes rsvp via paypal) b/c this group is much larger than mine, typically 50 odd people go to each event, they are held in public places or party rooms requiring reservations and sometimes a fee. Charging the fee makes people accountable for their rsvp.
I certainly hope the meetup owner in the OP charges in advance to hold people accountable for their RSVP. He could be cooking for 10 yes RSVPs and then only 6 show up. Yet he cooks for 10.
It doesn't sound to me he is running it as a business. I think he is just recouping his costs. If the meal is great, I would have no problem tipping a few bucks. He opened his home and spent a great deal of time cooking et al.