Why are there always more producers than consumers in a food chain?

At the base of each food chain, there are producers, namely autotrophic organisms, ie capable of organizing the chemical compounds in the soil (or water), so as to independently produce food reserves (sugars, starch). This process can be achieved by using the energy provided by photosynthesis. The producers are the only living things that can convert solar energy (light energy + thermal energy) into chemical energy (binding energy).