Chances of admission to top 50 university with excellent grades but few extracurriculars [WI resident, 4.0 GPA, 1520 SAT, 34 ACT, <$40k; social sciences]

Pretty high because they’re mostly about grades and rigor, but the interview (an oral exam with lots of questions about current events&politics in your geographical area of interest, ie., France, Europe, the US, and/or South East Asia, China, etc. +the mire typical “why us” question) Throws an element of uncertainty into the mix.