Overindulgence in business clogs the mind:[1]
Overindulgence in business leads to the mind’s transformation from a spiritual receptive limb, to a coarse and corporal limb. When one indulges too much in his livelihood, and is constantly looking for more and newer ideas of making money, it can lead to him thinking that it is his strength and might that brings him the income. This removes one’s trust from Hashem and makes his mind become coarse. His mind is not able to naturally grasp spiritual matters due to this coarseness.
[1] Likkutei Torah Chukas 66b