Parshat B'Shalach: Money makes you insane
Pharoah had had enough of the Jews and the trouble they brought with them. He finally agreed to let them go.
Now that they are gone, and he sees they are not coming back, Pharoah decides to chase them down. Not because he wants them back - he doesn't (according to Rashi in 14:5, at least) - all he wants is the valuables they took with them.
In verses 6 and 7, which is still before Hashem hardens his heart, he decides to chase them down. The pasuk says he gathered all the chariots in the country, including 600 top level chariots, and filled them with his officers.
I don't know if this was the whole Egyptian army, or just part of it. It is at least a significant portion. Add to this the fact they they were still licking their wounds form the plagues - a lot of people died in the Plague of the Firstborn, they might be weak from lack of food as crops had been destroyed and cattle had died in plagues. They are in a pretty prone condition and weakened state.
Yet Pharoah decides to go with a strong force to chase down a bunch of slaves for some jewels. I would even dare say that this was not a great amount, relative to what Egypt still had - we see by the splitting of the sea that they had brought tremendous amounts of valuables with them.
Egypt is in an extremely weakened state, and very prone. They had been the leaders of the world. there must have been other countries chomping at the bit waiting for this opportunity to attack and take over control of such a powerful country.
yet Pharoah leaves Egypt largely unprotected and vulnerable. Just to chase down some slaves to retrieve some money? It doesn't make sense.
I would suggest that this shows us how money can drive a person insane and make him think irrationally.