rich – богатый, ценный, тучный, обильный, см. «ric», «reach», «regime»

rich (adj.) (староанглийское «rice» - сильный, могучий, великий, высокого ранга, позже – богатый); из протогерманского *rikijaz; из PIE корня *reg- двигаться прямо, управлять, руководить
Old English rice "strong, powerful; great, mighty; of high rank," in later Old English "wealthy," from Proto-Germanic *rikijaz (cognates: Old Norse rikr, Swedish rik, Danish rig, Old Frisian rike "wealthy, mighty," Dutch rijk, Old High German rihhi "ruler, powerful, rich," German reich "rich," Gothic reiks "ruler, powerful, rich"), borrowed from a Celtic source akin to Gaulish *rix, Old Irish ri (genitive rig) "king," from PIE root *reg- "move in a straight line," hence, "direct, rule" (see rex).

The form of the word was influenced in Middle English by Old French riche "wealthy, magnificent, sumptuous," which is, with Spanish rico, Italian ricco, from Frankish *riki "powerful," or some other cognate Germanic source.

Очередное использование слова «рука».