Just because the human animal's learning rate is dropping from the moment they are born. If we could take 3 yr olds they would find it easier.
On your course you will find that the 19yr old gits will do very little work, come in hung-over etc and unprepared and still get through whereas you with your life experiance have probably developed a decent work-ethic by now and will need every bit of it. It doesn't mean you won't win the prize, but boy will you have worked for it!
It's the truth behind the saying about old dogs and new tricks.