赌

Left indexing shell radical 贝 (Kangxi #154 simplified) - historically cowrie shells used as currency. Anchors 赌 in the money family alongside 财, 货, 贵, 购. Carries the meaning core directly: gambling is staking money on an outcome. Without the shell radical, 者 alone would be a person; add the money and you get the picture of a person with their stake on the table.

Right component supplies the sound: 者 zhě → dǔ through Old Chinese sound shift. Same phonetic in 都 dōu / dū (all / capital), 著 zhù (manifest), 堵 dǔ (block), 睹 dǔ (witness) - a wide phonetic family. The 'person who...' meaning of 者 plays no role here; treat as pure sound.