Using my personal experience UConn's outreach to alumni has been totally lame in the past. Their ability to identify and cultivate medium sized potential donors has been non existent from what I can see. I am not a billionaire by any means, but had a very successful career in finance after completing my MBA at NYU. Most people are more likely to donate to their undergraduate alma mater than their graduate school. In my case it is just the opposite. I have never been approached by anyone from UConn, I get the annual mailings, while NYU is in contact with me on a regular basis. The net result is that I have made small contributions to UConn from time to time, while my cumulative giving to NYU is approaching six figures. Hell I hear more from the private schools and colleges my kids attended than I do from UConn.
A lot of of public universities have this issue. My undergrad alma mater (University of Illinois) has one of the better public university endowments in the country, yet their overall fundraising approach pales in comparison to the regular shakedowns in all forms of communication that I receive from my law school alma mater (DePaul). Part of it is culture - private schools (many of which have religious connections) simply aren't shy whatsoever about asking for money constantly and regularly (akin to tithing). Meanwhile, public universities have to fight the perception that all in-state residents are already giving them money in the form of taxes (which anyone that pays attention to higher education ought to realize is a misguided perception with how much public funding has been cut over the past 15 years, but it's still there).
Note that the endowments for the vast majority of schools aren't really tied that much to athletics. Texas and Texas A&M are in an entirely different category altogether because they were granted land ownership and oil/mineral rights to vast tracts of state land back in the late-1800s via the statutory Permanent University Fund. Those grants of land associated oil/mineral rights have turned out to be worth billions upon billions of dollars over 100 years later, which is why now they have the top 2 public university endowments. Many of the SEC schools with rabid football fan bases don't have the largest endowments, either. The public universities that have the largest endowments tend to be the ones with the strongest engineering/science/medical research functions (see how Pitt ranks higher than Penn State and Purdue ranks higher than Indiana despite PSU and IU having much stronger athletic fan bases compared to their in-state rivals). That's highly correlated with P5 membership because P5 members tend to be large research institutions, but historic power conference membership isn't the primary *cause* of larger endowments. It certainly helps, but not nearly as much as having a strong engineering program or medical school (or simply being made of a lot of old money like UVA).
That being said, I'm extremely surprised by UConn's low endowment compared to a lot of other public universities. It can't be passed off as supposedly a Northeastern regional phenomenon of not supporting public universities (whether it's sports or academics) because schools like UMass, SUNY Buffalo, New Hampshire and Vermont all have larger endowments than UConn. UConn is a better undergrad institution than all of those schools while having the wealthiest state population base in the country, so it certainly isn't due to the success of their alumni. That points to UConn definitely underachieving on the fundraising front (and it doesn't have anything to do with athletics, as you guys should definitely be doing better than SUNY Buffalo regardless of whether you're in the AAC).