increase lower canopy air circulation. its like rotting.
and get rid of the dead leaves
drying out too quick is an interesting theory. i dont think its right. wouldnt the plant die from the top? we dont know his watering schedule
altho that dirt does look mighty dry on top and could probably benefit from some help
it could be diseased not sure-
Potassium deficiency (K).ww
Older leaves are initially chlorotic but soon develop dark necrotic lesions (dead tissue). First apparent on the tips and margins of the leaves. Stem and branches may become weak and easily broken, the plant may also stretch. The plant will become susceptible to disease and toxicity. In addition to appearing to look like iron deficiency, the tips of the leaves curl and the edges burn and die.