To understand Kṛṣṇa is not very easy job. Kṛṣṇa says: "Out of many millions of men, one is trying to become perfect in this human form of life." Not everyone is trying. First of all one has to become brāhmin or acquire the brahminical qualification. That is the platform of sattva-guṇa. Unless one comes to the platform of sattva-guṇa, there is no question of perfection.
Nobody can understand, nobody can achieve perfection on the platform of rajo-guṇa and tamo-guṇa, because one who is addicted with rajo-guṇa and tamo-guṇa, he is always very greedy and lusty. Tato rajas-tamo-bhāvāḥ kāma-lobhādayaś ca ye (SB 1.2.19). One who is infected with the material qualities of ignorance and passion, he is lusty and greedy. That's all.
Therefore you will see, generally, people are very much lusty and greedy. They are accumulating money, crores and crores; still, they are not satisfied. In Western country we see very usually. There are many, many workers, working very hard from very poor state. Just like Henry Ford, Mr. Rockefeller, they started life from a very humble state, but they accumulated immense wealth, and still, they were not satisfied.
In our country also there are many Birlas and such, accumulating money, money, money. They are greedy because infected with the quality, modes of nature, ignorance and passion. Vaiśya means passion and ignorance, kṣatriya means passion and brāhmins means goodness. These are the different qualities.