Thank you for the comment Shajey!
I agree with your mentor. I recall my aerospace engineering years and I studied almost everything by myself at home. University is valuable to make friends and get an official degree (it may not be required for some jobs, but it's a from of insurance).
The problem is that the cost can be prohibitive in the US. I live in Spain and it's not that bad here (although it should be better for sure).
What did you study in the end? :)