SSP's acceptance rate is about 10%

Applications to SSP are very competative.
It's acceptance rate is about 10%, roughly the same as the acceptance rate of the lower Ivies.

My kid attended SSP in New Mexico Institute of Technology in the summer of 2018.
Out of the 36 kids in this program, 6 were accpted by MIT, 5 by Caltech, and 4 by Harvey Mudd in 2019, in addtion to at least 3 each by Harvard and Stanford.