Dwarven Thinking 101

[Maedhros]

Dwarven Thinking 101
From The Lord of the Rings: Appendix III Durin’s Folk

Years afterwards Thrór, now old, poor, and desperate, gave to his son Thráin the one great treasure he still possessed, the last of the Seven Rings, and then he went away with one old companion only, called Nár. Of the Ring he said to Thráin at their parting:
'This may prove the foundation of new fortune for you yet, though that seems unlikely. But it needs gold to breed gold.'

When Thrór came to Moria the Gate was open. Nár begged him to beware, but he took no heed of him, and walked proudly in as an heir that returns. But he did not come back.

Such was the tale that Nár brought back to Thráin; and when he had wept and torn his beard he fell silent. Seven days he sat and said no word. Then he stood up and said: 'This cannot be borne!' That was the beginning of the War of the Dwarves and the Orcs, which was long and deadly, and fought for the most part in deep places beneath the earth.

Thráin at once sent messengers bearing the tale, north, east, and west; but it was three years before the Dwarves had mustered their strength. Durin's Folk gathered all their host, and they were joined by great forces sent from the Houses of other Fathers; for this dishonour to the heir of the Eldest of their race filled them with wrath. When all was ready they assailed and sacked one by one all the strongholds of the Orcs that they could from Gundabad to the Gladden. Both sides were pitiless, and there was death and cruel deeds by dark and by light. But the Dwarves had the victory through their strength, and their matchless weapons, and the fire of their anger, as they hunted for Azog in every den under mountain.

It is very interesting to analyze this. We have first that in 2590 TA Thrór goes to Erebor, and in 2770 TA Smaug lays waste to Erebor, but Thrór escapes with his son Thráin and Thorin. Then in 2790, Thrór in his old age, get this idea of trying to amass more riches and become wealthy in Moria, but is slained in there by Azog, thus creating a great enmity between Orks and Dwarves that led to the War of Dwarves and Orks which began in 2793 TA.

Look at what happened in the end of that War:
From The Lord of the Rings: Appendix III Durin’s Folk

When at last the battle was won the Dwarves that were left gathered in Azanulbizar. They took the head of Azog and thrust into its mouth the purse of small money, and then they set it on a stake. But no feast nor song was there that night; for their dead were beyond the count of grief. Barely half of their number, it is said, could still stand or had hope of healing.

More greed?

Dwarf behavior in the Narn:

Again pity long hardened welled in Túrin's heart as water from rock. "Alas!" he said. "I would recall that shaft, if I could. Now Bar-en-Danwedh, House of Ransom, shall this be called in truth. For whether we dwell here or no, I will hold myself in your debt; and if ever I come to any wealth, I will pay you a ransom of heavy gold for your son, in token of sorrow, though it gladden your heart no more."
Then Mîm rose, and looked long at Túrin. "I hear you," he said. "You speak like a Dwarf-lord of old; and at that I marvel.

From The Hobbit

"No!" said Thorin. "There is more in you of good than you know, child of the kindly West. Some courage and some wisdom, blended in measure. If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. But sad or merry, I must leave it now. Farewell!"

Thorin in the end realized that his values were not as good as those of the hobbits who valued other things above gold. Now it makes you wonder, why would all of those Dragons went to slay of all those dwarven kingdoms? Why not go to Mirkwood or The Shire instead?
I ask you again, was greed the cause of their diminishment.