One should not spend one's time pondering over earning money. That is a misuse of the thinking power
Bhagavad-gita As It Is
BG Chapters 7 - 12
Control of the senses means that the senses should not be used for unnecessary personal enjoyment. There is no prohibition against meeting the proper needs of the senses, but unnecessary sense enjoyment is detrimental for spiritual advancement. Therefore the senses should be restrained from unnecessary use. Similarly, one should restrain the mind from unnecessary thoughts; that is called śama. One should not spend one's time pondering over earning money. That is a misuse of the thinking power. The mind should be used to understand the prime necessity of human beings, and that should be presented authoritatively. The power of thought should be developed in association with persons who are authorities in the scriptures, saintly persons and spiritual masters and those whose thinking is highly developed. Sukham, pleasure or happiness, should always be in that which is favorable for the cultivation of the spiritual knowledge of Kṛṣṇa consciousness. And similarly, that which is painful or which causes distress is that which is unfavorable for the cultivation of Kṛṣṇa consciousness. Anything favorable for the development of Kṛṣṇa consciousness should be accepted, and anything unfavorable should be rejected.