Istan bhogan hi vo deva dasyante yajna bhavitah
tair dattan apradayaibhyo yo bhunkte stena eva sah
(Text 12, Ch 3, Karma Yoga)
Meaning : In charge of the various necessities of life, the demigods, being satisfied by the performance of yajna (sacrifice), will supply all necessities to you. But he who enjoys such gift without offering them to the demigods in return is certainly a thief.
*** We should make proper use to all necessities supply to keep ourself fit and healthy for the purpose of Self-Realization, leading to the ultimate goal of life (Liberation from the material struggle for existence). This aim of life is attained by performance of yajnas. If we forget the purpose of human life and simply take supplies from the agents of the Lord for sense gratification and become more and more entangled in material existence, which is not the purpose of creation, certainly we become thieves, and therefore we are punished by the laws of material nature. A society of thieves can never be happy, because they have no aim in life.