Because if youngcels knew the truth, they would give up on life before universities/corporations/governments could profit from their studymaxxing and wageslaving.
The only reason I bothered studying in high school and college was because I naievely believed the lies that adults told me back then ("You'll have to beat women off with a stick when you earn that degree and begin your professional career.") After realizing that was a load of tosh, I got off the corporate treadmill and now alternate between NEETdom and working much lower-stress jobs than I did in the past.
My younger brother saw how working stressful jobs wasn't paying dividends for me, so he wisely opted to drop out of college in 2007 and has been hikikomori ever since. All he does is play video games and hasn't submitted a single job application this entire decade that's close to being over.
Society gets the men it deserves.