IMO CG and Silvia should take part of the blame. AFAIK Carl Philip is nearly the only spare in his age group who does not do something "useful" with his time.
Harry: joined the army at one stage
ML: Mom to three girls and talks to angels
Constantin: Works despite his family being loaded and so did Friso
Jokke: Stands in all the time if his brother is not able to roll out of bed, was a farmer
Elena: okay, ... another a bit lost cause, but at least keeps a low profile
Felix: makes wine
Have I forgotten anything? Alexander most likely will have to work for a living, so it would be good if his parents were a great example to him and would not throw glass bubbles into wine glasses and call it "design".
I guess in the Netherlands it became clear that the spare and the following ones needed to be self sufficient. Ok they had some pro's and extra's which came with being a royal and coming from a rich family. Among others easy to get to specific positions than others.
In the past, as a child and teenager, Friso already expressed not happy being the spare. As a child he even remarked about Willem-Alexander: "Je mag Alex wel in elkaar slaan, maar niet doodslaan, want dan moet ik koning worden" (= "You may well beat up Alex, but not kill, because then I should be king").