Status. If you're from a rich family, you're been told that you have all this wealth and privilege and all the advantages that comes with it. You are not going to let your dumb kid ruin it all for you.
At least with Asians families, parents fucking trade which kid went to which college like fucking Pokemon cards. The day I told my mom I'm going to UCI and UCSD, and the local CSU, she told me that I had to choose between UCI and UCSD because she needed to brag to her friends.
And my family were poor as fuck. I can't imagine the pressure on some of these kids that actually have some money to spend on dumb shit like private tutors, SAT camps, etc.