> If you mean in term of quality of life, I actually think that in absolute terms it is probably marginal

You are severely underestimating the importance of peace of mind. When you are poor, you are always worried about making rent. When you are middle class, you might be a few paychecks (or a hospital bill) away from insolvency. The wealthy don't have to worry about those things.

John Scalzi has an awesome post about the cost of being poor[1] on his blog.

http://whatever.scalzi.com/2005/09/03/being-poor/

Edit: d'oh, my reply is off-topic because I misread GP's post - missed that the distinction is between 1%ers and 0.1%ers. Considering that; I suspect the difference is in influence (my guess is the 0.1% are likely to be more 'politically involved' or better connected)