All I'm attempting to do is chronicle two thousand years plus of british coinage so not ambitious at all...on top of that I also collect British imperial / colonial coinage.
I suppose the why is because I am interested in all areas of history & it excites me to attempt to weave together all these periods of British coinage into a singular story reflecting the wider history of Britain.
I should also say that I studied history at Uni & nothing has been a greater spur since I graduated for me to learn more about specific areas of history than coin collecting has. I now have a broad knowledge of many areas I never would've otherwise had because, in my opinion, you must educate yourself about what you're collecting or, at least, it's way more enriching if you do.
At least I'm accepting of the fact I could never collect everything I would want to in my one lifetime so the aim can only be to go as far as I can in achieving that.
Like the OP, I am also putting together a hard print copy of my collection & to record all the knowledge I have gained along the way as at the moment, all that information is spread across various places: books, websites, spreadsheets, word docs & of course, my own head. It is quite a undertaking but then again, I've got no deadline by which to finish it so that obviously enables me to take my time. It will also be an ongoing process as the collection will be continuously added to which means the hardcopy catalogue will also have to be frequently updated.