the money just evaporates for consumption

Right! A small fraction of debt repayment might show up as spending from financial sector executives' bonuses, but most, even of this money, is deployed back into more financial ponzi schemes. If it went back into investment for social overhead capital or domestic production capital it would help, but, with current financial realities, it is more likely to go the investments in the BRICs, where it generates better returns for the owners of the capital. Your (formerly) 1st world domestic economy only serves as a target for wealth extraction, not a site for wealth creation. This is true in Spain as well as in the USA.

Workers of the world, ....

"It is not necessary to have hope in order to persevere."

And if the lender has an underwater balance sheet, the money that is repaid will go to pay for spending that is long in the past -- unless there is a default.

"It is not necessary to have hope in order to persevere."