While I know of no chiropractic college that retains a billion dollar endowment, I believe each one would benefit from having an endowment of any size. Some schools plow unspent tuition revenue at year's end into an endowment fund. Such action may seem unfair to the current students, but it helps to ensure the long term viability of the institution. The most obvious source of endowment funding is through gifts and donations. With varying degrees of effectiveness, every college president has asked someone to make a donation to their respective school.
Most colleges support a fundraising or development office on campus.
Through that office, a variety of fundraising efforts are launched. The more common programs are annual programs where alumni and friends of an institution are asked to give a yearly donation, usually at year's end, to take advantage of a tax savings. This is an inexpensive way to solicit donations, but it is also one of the lease successful methods. Its greatest advantage lies in the identification of willing donors who may be able to give more if asked. There is money to be found in these sources, but it is difficult to acquire.