Misunderstanding

Peter had not given up on web-shooters. Although he could produce spider silk himself, it was made of protein and required him to expend his own energy to create and synthesize it. He would have to study the specifics to know for sure. In any case, no matter the result, the spider silk he produced himself definitely could not be generated infinitely and without cost. Whether it was magical energy or biological protein, something always had to be consumed.