I don’t remember off hand whether the 5,000 talents Harpalos requisitioned before beating his way out of Babylon were of gold or silver, but in either situation it is a lot of money and weighed a lot. For those who don’t know the story, this guy really liked to spend money–more than any trophy wife I have ever heard of– and when Alexander was returning from India he was also punishing people who were corrupt. Harpalos, the treasurer for the entire empire, decided to run away rather than face his cousin and left Babylong with 5,000 talents, which weighed around 140 tons.
If these talents were of silver, then the rough modern estimate for value is around 32.5 million dollars US. That is a lot of money, but not that huge an amount. Yes, it is enough that Alexander probably had to go chase him down and try and get it back, but not a jaw dropping amount (outside of the weight).
If the talents were of gold, however, the lower end for modern estimated value is 1.5 billion dollars. Yes, billion. The upper end for the estimate is around 3.3 billion. This amount is absolutely ridiculous and with that amount of money Harpalos could quite effectively make friends to oppose Alexander. Now I would be pissed if someone stole 32.5 million bucks from me, but I would be hiring hitmen and hunting that bastard down myself not even pausing to eat, sleep, or anything if someone stole 1.5 billion, let alone 3.3.
Yeah, that is a lot of money.
I am also willing to state right out that I think Diodorus has his wires crossed when it came to the Egyptian treasury Ptolemy inherited. He says that there were 80,000 talents in Egypt. If it was all silver that is around 520 million dollars, if all gold the upper limit is around 52.8 billion in modern equivalence–that is the amount saved, not the amount of income. Hyperbole anyone?