Naive is not always the same as simple. Do I really need a car? And do we need so many NEW cars? If you are selling cars, you would say yes, because new cars have bigger margins and profit. The market is flooded with brands and choices. New is marketed as better. But tons of old ones that are doing fine are discarded, wasted. Keeping up this growth in demand for new products and thus resources is artificial and benefits no one but the ones who can scrape the most of the margins. It is not the consumer nor the employees that benefit. The company might benefit a bit, but it is mostly the investors that have lend the money to the company that get the biggest part of the cake.
I'm really not sure what your argument is now. You seem to be proposing a return to more or less medieval methods of finance and operation. Practically every industry depends on the funding services provided by banks: are you suggesting that medicine, food production, transport, housing, mining, etc. should all operate on the basis of using current cash in hand only?
'Cash in hand' is not what I propose, with bitcoin, you have a whole Bank in your hand, that is not my idea but the one of Satoshi. It is not back to medieval methods, but forward to a truly free revolutionised economy. Humanity has had several revolutions, the philosophy and sciences have revolutionised thinking and relieved us from most dogma's we used to live by, the industrial revolution, the digital revolution and now the economical revolution, it will take big steps into the future. We do not need banks for investments, we do not need banks to store large sums of money, all because of the cryptocurrency. If we do not need banks, they no longer can sell us loans and they will no longer provide companies with money to enforce products we do not actually need. We will be our own banks, we will dictate on what we will spend our money, where we want to invest and what we think, for ourselves is worthy of being produced.
The next step ofcourse is home production, where we can buy just the resources and make our own product at home. 3D printing, from a pencilbox to complete houses. The future is now and it is evolving rapidly