These are all ostensibly people with high-upper-quintile incomes at minimum. Is it really out of line to just have everybody pay their own lunch check?
No, that's fine, and how things operated for years. Not sure how free lunch really helps attract more folks. However, that doesn't help with other infrastructure like the website, unless you want to ask organizers to pay out of their pocket.
You'd have to ask Miles (who commented above) why he made the switch to sponsorship.
I replied directly above, but the other reason sponsorship is attractive is because it's hard to host a group of 20-30 people for lunch usually.
We've lucked out in Boulder & Denver where we can make a reservation for that big, but a lot of places I've talked to want event fees, so I'm still going to avoid that, but it'd be nice to have the option.
I would give up "free lunch" to have the sponsorship funds going to improving the community interaction. Lunch is ephemeral yet peer mentorship is priceless.
It's definitely not too much to ask for people to pay their own bill at lunch, but my goal is to continue to add value to the group, which I think will become easier if there are more resources at the group's disposal. More cities, more engineering leaders to get advice from or make connections to, etc.