Here is a little LaTeX visualization I made to better convey the simpleness of learning, life and the world in the the internet. In even plainer terms, we can see in order to learn something (ideally a hard skill set or task- soft and meta skills are iffy on the internet at best) we must spend a certain amount of time on the internet and a fair amount of time on task, with all both of these things getting larger in size as standards for quality and ambition of work go up. In order for all this "work" to equal the desired learning, we divide the three factors (Time, Standards, Ambition) by the difficulty of the task at hand.
It is easy to set ambitions with great difficulty (in funtwo's case, learn guitar to do a neoclassical shred of a pachelbel tune) but as the steps get broken down into smaller day-to-day and minute-by-minute gains in ability and knowledge, the difficulty factor must be incremental enough to be attainable, but difficult enough to be engaging. Thus, this model can scale from the: 35 minutes (Time) on youtube (internet) learning guitar scales for sweeping techniques with good form and in complete scales (Standards) divided by the goal to maintain and enhance a current harmonic minor scale (Ambition) that has been the focus all week, which is incrementally more (difficult) than the "not sweeping the normal minor scale" that was last week's project and success success... ...To the 3-5 years of diligence it took funtwo to gain mastery of both guitar and the arrangement.
So, moral of the story is you do not need "prerequisite understanding" that can only be bought for $20k at a university near you to master whatever it is you need to master (Though these institutions are good for lots of other things though, that IMHO do make the visit worth it).
Anyone can do anything if they understand the factors that go into high craft, artistry, and learning.