> On the other hand, at 7200 RPM, it takes up to 138 microseconds to wait for the platter to spin around and reach a random block on the same track.

You did the math for 7200 rotations per second, not 7200 rotations per minute = 120 rotations per second.

In gaming terms, you get at most one or two disk reads per frame, which effectively means everything has to be carefully prefetched well in advance of being needed. Whereas on a decade-old SATA SSD you get at least dozens of random reads per frame.

Fixed!