Do you need 10 great ECs to get into top colleges?

[mikemac]

From what I’ve seen, most admits to these places have been able to max out their commonapp activities section with great extracurriculars, so I’m worried that I’ll be at a competitive disadvantage when compared to them.

Not sure where you got your info, but it’s not right. As Stanford says

Students often assume our primary concern is the number of activities in which one participates. In fact, an exceptional depth of experience in one or two activities may demonstrate your passion more than minimal participation in five or six clubs. We want to see the impact you have had on that club, in your school, or in the larger community, and we want to learn of the impact that experience has had on you.