Cal State San Marcos started as a branch campus of SDSU (the Mountain West school). It became independent in 1990.

I think it was started for nefarious reasons. The Cal State system requires each college to admit any student who graduates in the top 1/3 of their high school within the college's geographic district. That's a really low bar for the best CSU schools (SDSU and Cal Poly). Southern CA high schools are comparable to high schools in rural Mississippi/Appalachia, so finishing top 1/3 in most local high schools does NOT mean you're ready for college. They'd rather save their spots for students who pay out-of-state tuiition. So SDSU started San Marcos with the intention of eventually cutting the size of their district in half.

Today, CSU-SM is a small commuter school (13,000 students). There's little campus life. It's mostly composed of students who didn't have the SAT scores to get into SDSU, and whose high schools were out-of-district for SDSU.

FCS is a pipe dream for them. It's a glorified community college. It makes SIU-Edwardsville look elite. It's like NKU 30 years ago before they ended open enrollment.

Even D-1 basketball is a huge stretch, especially because it's in a region that doesn't support its sports teams.