I'm lucky in that two clubs I belong two, neither cycling clubs, are very welcoming and both are thriving. I suspect the one leads to the other. On of these clubs is a camera club and I'd 'shopped around' before deciding to join this one. One of their local competitors reply started their reply email with:-
'We are a serious club using Canon equipment' enough said. The club I joined has the usual Canon and Pentax rivalry, but one of our best photographers uses Sony, several members use Bridge cameras and I use Olympus, in fact almost all of the manufacturers are represented within the club. They run winter courses for beginners most years, last winter was for intermediate users and nearly all of the usual faces turned up for those, even though some are certainly well beyond intermediate photographers!
It's all down to the inner ethos of the club and sadly too man, in all hobbies, are run as ego trips for the few.