My kids play a sport (soccer) that has players with a really wide income disparity, and this has come up several times (and, in fact, is the reason why I am often "team mom"). My position is "this is a team sport, and whatever we do will include every member of the team" which often means that travel/tournament fees for some players is subsidized by other families. Or we do fundraising so everyone can be part of ... whatever the thing is. And I talk about this explicitly, both with my kids and with other families when I'm asked.
Since you're pushing against someone who has already volunteered for the job, I'd suggest taking nereo's advice and reaching out to the organization. It makes no sense for them to be driving families away because some folks want to spend even more on quasi-team activities, so see if you can get some support from the club! Also, you can offer to take over some things: pizza for a team can be pretty inexpensive, and it's still a "team dinner." There are probably ways to sidestep some of the issues by just finding less expensive ways to fulfill the "team activity" idea.
If at all possible, you might consider having the team do a couple of volunteer activities: they can serve dinner at a shelter, or make sandwiches and hand them out to people on corners, or help move pallets around a food pantry, or tutor smaller students (or teach lessons in whatever-your-sport-is).
I was delighted when my older son, who was then a captain of the high school team, arranged that the warmups for some of the players were subsidized by other players, so everyone got matching jackets. I was even more delighted that the coach and I were on the same page, so we did some additional fundraising so that all the players had access to the same opportunities and stuff. (And that the "stuff" was pretty minimal, honestly -- because it's not essential to doing the sport!)