Yeah your soldiers eventually want to retire and spend all that loot they got to live in luxury rather than run the risk of dying in more war. They’d been at it continuously constantly for over a decade and India looked like a tough nut to crack with massive forces like the Nanda Empire up ahead and even relatively petty king Porus had put up a stiff resistance that killed a decent number of Greeks.

Later on one of the prominent warlords (Eumenes) was betrayed by these men because, even though he otherwise came off better in a fight against rival warlord Antigonus, the all important baggage train containing decades of booty, wives and kids was captured. So the veteran silver shields who are mostly old farts by this point mutinied and delivered him bound to the rival warlord Antigonus to ensure their long years of war would not be in vain.

This meme implies that his match was the geography of India, not his army.