People give loans when the future is bright & the future is bright when people get loans.
People only continue to act in good faith (making and repaying loans, making purchases beyond what’s absolutely physically required) when they feel that their future is bright. If the pie is not growing, suddenly the world becomes a zero sum game, and your gain is my loss. The growth we are enjoying is somewhat self-sustaining. However, It is also true that stagnation begets stagnation.