Maslow's Hierarchy in action - Tim Cook is at a higher section of the pyramid than most Americans. He's probably at a stage where he's looking to achieve things he cannot achieve purely with money. Hence the "money isn't everything" argument.
1 - https://www.td.org/Publications/Blogs/Science-of-Learning-Bl... 2 - http://tonyahn.com/2012/02/2012-needs-hierarchy-update/
It’s not like these students are in desperate debt (http://www.heraldscotland.com/news/14562911.Scottish_student...: the average debt of Scottish graduates in 2014/15 was £10,500), or have to pay back those debts soon (http://www.bbc.com/news/uk-scotland-40353399: For example, someone earning £21,000 a year would pay back £24 a month)