The most common reasons your money tree is losing it's leaves is due to poor light conditions, improper watering such as over watering or under watering of the money plant, fluctuations in temperature and even possible pests or disease.
Over watering the money tree or money plant or even under watering the money plant can cause the leaves to die out and fall off.
Over watering of the money plant, causes the money plants roots to rot, and causes the money plants leaves to droop and drop.
Waterlogged soil of the money plant can also suffocate the money plants roots, and prevent them from absorbing the nutrients it needs to survive and lead to yellowing of the money plant leaves and leaf drop.
Under watering of the money plant causes the money plants leaves to dry out and turn brown and drop.
You should allow the top inch or so of the money plant soil to dry out between watering's of the money plant.
Money plants require bright and indirect light to survive and having too much direct sunlight can cause the money plant leaves to burn and too little indirect sunlight can cause the money plant leaves to yellow and cause leaf drop.
And sudden changes in the light by moving the money plant can also cause stress and leaf drop.
Also sudden temperature changes can cause the money plant to lose it's leaves.
Money plants are very sensitive to drafts and fluctuations in temperature, which can stress the money plant out and cause the leaves to drop off.
And low humidity can also cause the money plants leaves to dry out and drop.
And even pests such as spider mites can cause the leaves to become damaged and cause the money plant leaves to drop and fall off.
Or if the pot does not drain well, the roots of the money plant can rot and lead to leaf drop.
Or if the money plant has nutrient deficiencies and does not get enough nutrients, the leaves of the money plant can turn yellow and drop and cause the money plant to lose it's leaves.