Achieving achdus with other Jews in the community is much easier when you live OOT and are outnumbered by the goyim in great multiples.
Those of us business owners and professionals frequent one shul, but typically belong to all and donate to all the Jewish institutions in the community…Chabad or Schecter Day schools, all shuls, the JCC, Federation, Hadassah, B’Nai Brith, Hebrew Free Loan/Burial, Jewish Family Service, etc.
Presenting a united front is very important in galus.