Geography helps also. Greenwich CT is a few exits away on an interstate highway from Bridgeport CT, but the composition of the public HS’s could not be more different. The name of your HS is an important signifier.
On the “dipping into the endowment”- that’s not how it works. A high percentage of endowment funds are restricted- if you’ve donated to build a nanotechnology center with an endowed professorship, the U can’t “dip” into that endowment to pay for financial aid for a freshman from Camden NJ. “Dipping into their endowment” happens monthly. Prudent financial management is going to even out the revenue stream that way. But a donor giving to Harvard’s Divinity School isn’t supporting undergrad financial aid…