The millionaire peasant

So your character starts with a million GP. This post has created a great deal of feedback. Some very valid if viewed from our early 21st century outlook on life. A great deal of players have said they'd buy an castle and an army. This is a very understandable aspiration from our point of view, but it rises the following question:

Who the fuck is going to sell you a castle if you're a fucking peasant?!?!?!?!

Now my intention is not to trash those who commented along those lines, but rather to raise the issue of how immersed are we in the medieval setting. BTW, I'm not using immersed in a game theory way so don't trash me back. I'm simply wondering how well players dive into the setting of a medieval society.

If you have a million gold pieces to start you already have a good social standing. Otherwise you're just a bandit, or maybe some bourgeoisie of an era still to come. With a million GP you're certainly a noble and maybe a courtesan. You'll probably be skilled at fighting, but you'll have others do the fighting for you. You will lead, and leading will exercise those atrophied aspects of D&D. You know which, charisma and that sort of stuff.

Sit back and think about what it meant to have power in the middle ages. Was it just gold? Does gold make you powerful or just a rich bandit? Who conspires in court? Who negotiates the deals? Who leads the armies? Is it the +3 attacks, x2 damage, 3d12 + 2xSTR bonus fighter or the cunning noble with an even cleverer player behind him?

Images
http://www.whiteoak.org/wp-content/uploads/2012/09/Medieval_Morons.jpg