As part of being a "Non-Profit" an organization must show that it spends all that it receives (more or less) on projects to benefit the community/its cause.
So as not to have piles of cash in the bank, you can tie up these assets in real estate in the guise of various projects "for the benefit of members"
Should the need arise the property and buildings can be sold off, for a profit and free of tax, to gain access to the invested monies.