That's arguably part of the library's mandate. People learn how to think, how to research, how to speak, how to organize, how to write, how to overcome shyness. People make new business contacts, and new friends. Fundraising campaigns are a community service to many of the volunteers. Fundraising builds communities.
People discover they can get money, and feel empowered.
They learn to work in teams. They go on to tackle other problems. People need to give. Stewardship means we all have something to give, and if we don't use our gifts, we are poorer for it. The people who use the library need to know they aren't getting something for nothing.