I think any parent still mad at a kid for not getting into a given college or a certain athletic conference in the Northeast is out of line, especially if that kid had good grades, was active outside class hours, and spent a fair amount of time on his/her essays. I was lucky - I got into my first choice. At my school, I’ve seen qualified students accepted, others rejected, and one patently unqualified student accepted to an Ivy through some combination of wealth and family connections (not legacy). It’s not a pure meritocracy, or anywhere close to it. Doing well in school and being active outside the classroom is within a kid’s control, and if (s)he doesn’t do that, parents can take issue. Blaming him/her for the results of a black-box process is absurd.
It seems to me that OP’s parents were eagerly trying to keep up with the Joneses throughout high school. When OP wasn’t accepted to the almighty Ivies, instead of saying “Yikesyikesyikes got into Michigan, and it’s a great school. The next four years look wonderful,” the talking point became “Yikesyikesyikes got into Michigan, and (s)he’s hoping to transfer to Ross after a year,” because by some arbitrary definition of prestige name-dropping Ross seemed more impressive. Now that’s gone. Hence the disappointment - they find it shameful that their son/daughter is attending a college among the top 30 in a country with 3,000+ of them. This is all uninformed speculation on my part, but it’s one explanation that could fit the facts as presented here.
I don’t usually tell people to “get over it,” but OP’s parents need to do just that. Half a dozen Nobel laureates, at least a score of Pulitzer Prize winners, and several current/former heads of state will vouch for the merits of a University of Michigan education