My wife and I are in this percentage. Both educated, making ok money but with a new family and undergrad loans still looming it feels like homeownership is still years away. I will probably be 35 by the time I can buy my first "starter home".
We are moving all around the country to find better and more affordable places to live. In fact now that my wife has her master's we're chasing clinics that provide loan repayment just so we can get our debt out from under us.
Another reason we keep renting - I've worked other industries that do poorly during a recession and tech feels no different. I'm highly predisposed to not being stuck with a huge mortgage when things get tough which means in a lot of cities I'd never feel comfortable buying a home (insinuating that we couldn't survive on one income).