द्यूतं छलयतामस्मि तेजस्तेजस्विनामहम्।जयोऽस्मि व्यवसायोऽस्मि सत्त्वं सत्त्ववतामहम्॥
dyūtaṃ chalayatām asmi tejas tejasvinām ahamjayo ’smi vyavasāyo ’smi sattvaṃ sattvavatām aham
Word by word
The verse says
I am the gambling of those who cheat. I am the splendour of the splendid. I am victory, I am resolve, and I am the goodness of the good.
In plain words
Read the first clause again.
Dyūtaṃ chalayatām — the gambling of cheats, of those who deceive.
That is in the same sentence as the goodness of the good, and no explanation is offered for it.
Where you've felt this · in failure
Your cousin lies well, and it is genuinely difficult work. He holds two versions of the evening in his head at once. He tracks who has been told what. He watches your face for the moment it slips. It is a real skill put to a bad purpose, and the skill does not become less real for that.
Going deeper
Claiming the cheating of cheats is the hardest line in this chapter and the traditions handle it differently.
One reading keeps it narrow: what is claimed is the power, not the purpose. The sharpness, the nerve, the quickness — these are real capacities, and the verse has been saying all along that every capacity has one source. On this reading nothing is being approved of.
A harder reading takes it as it stands. If he is the beginning, middle and end of everything, there is nowhere for deception to come from that is not also him, and the verse simply declines to pretend otherwise. This is the same refusal as Chapter 9, where rain and its withholding, and what lasts and what ends, were all claimed by one speaker.
Neither reading makes cheating good, and it would be dishonest to soften the line into something comfortable. What it does is close the exit where difficult things get assigned to a second power. The excellence in a bad act is still excellence, and the verse will not let you file it elsewhere.