Fund raising keeps an library involved and accountable. The outreach, the contact with the community, the debates, the demand for accountability, the activities are life's blood to a real community-based group. Better to give the money away then die rich. This is not only good organizational sense, it is one of Carnegie's principles of philanthropy. Too many groups are scrambling for cash and offend donors because they don't take time to say thank you and build strong relationships.
Money attracts money.
A million now will be like honey to the bears. Fundraising will never be easier, provided everyone knows what the money will do for the community. Potential donors might decide that if someone believed in the Y enough to leave them a million, there might be a good reason. Fundraising is never just about money. When people give they feel ownership.