How has this decision affected my academic career? (1 year gap) I will just project my mind here and see where it goes. A lot of this will seem childish/immature/ Due to various problems from a multitude of directions in my life; some serious, some idiotic (mid-life crisis at 18?! What the hell was I thinking); I decided to defer my enrollment to Imperial College London last year. I will now be joining the Theoretical Physics course this October. For some reason I felt I did not have enough life experience to go to university but I ended up getting a job in consultancy and have plans to travel for a while before going to uni in five months.

On paper it seems there is not much wrong but I am telling you it is not so. The pain of not learning anything new is a lesser one than others but still one I feel keenly. The knowledge of being behind on the treadmill of life compared to my friends is also worrisome. When I read about my lifelong idols (Feynman, Erdos, Einstein etc.), people I respect greatly, I feel for some reason I can never think on the same plane as them anymore due to missing out on a full year of education. I know how silly that sounds, but the feeling is there nontheless.

Either way, feelings aside, how will this year gap affect me career-wise? If there was an alternate-reality, naïve version of me who went to university straight away, what advantages would they have over me? What will professors think when when/if I apply for a PhD? What percentage of academics have also had a similar break, roughly?  

Basically I just want to count my losses and ensure I extract as much juice out of the next 5 years as possible, so I look upon this period as just part of my life rather than an ugly blotch. Thanks for reading.
A year more or less makes zero difference for anything that's more than a year removed from the reason to take the break.

You worry unnecessarily about the issue -- plain and simple as that.

(Now, on the question to comparing yourself with Feynman, Erdos, and Einstein: If you want to stay sane, you need to at one point come to the realization that these can be idols, but not a status you can aspire to ever achieve. They lived in different spheres, and the number of people at this level is minuscule. I think a lot of us who consider themselves reasonably successful in academic life had, at one point or another, a small crisis when we realized that our contributions will not amount to much 100 years from now -- and eventually came to the realization that that (i) doesn't mean that we can't have a satisfying life that includes other things we're proud of -- such as raising children, or just inspiring students, and (ii) that most of science is actually many relatively small steps, of which we can contribute many.)