Is abasement to other than God a sin, and does it entail the prohibition of wealth acquired by this method, and how can this abasement and subservience in dealing with others be removed?

The basic principle concerning professions and industries is permissibility, unless there is evidence to prove their prohibition. The feeling of abasement can be confused with humility, fear, shyness, and obedience. Humility towards Muslims is legislated, and fear of one's employer is not forbidden, but it diminishes the perfection of tawakkul (reliance on Allah). Shyness is part of faith, and obedience to the employer in matters agreed upon in the contract is obligatory. However, these virtues must not lead to condoning prohibitions or assisting in them, for there is no obedience to a creature in disobedience to the Creator, and a believer should not abase himself. If the work is permissible, does not aid in disobedience, and does not involve abasing oneself, then there is no harm in it. What you are experiencing might be waswasah (whispers from Shaytan), and the strong believer is more beloved to Allah.