I can believe that instruction typically comprises the largest share of costs per student.
One would hope that is the case, right?
Nevertheless, there does seem to be significant variation in the ratio of instructional costs to total costs per student. By my reckoning (using IPEDS data for instruction and the numbers cited above for total costs), instruction at Reed, Pomona, and Williams comprises 50%-59% of total costs.
Instruction at UChicago and Stanford comprises 91% and 93% of total costs, respectively.
Total spending minus instructional spending is ~$28K - $35K per student at Pomona, Williams, Yale, and Harvard. Total spending minus instructional spending is approximately $7K-$8K at Berkeley and UChicago.