Ж-78

С ЖИРУ БЕСИТЬСЯ coll disapprov VP subj: human or collect usu. this WO (of one who is deemed to have been spoiled by a satiated, idle life devoid of troubles) to behave in a fiissy, capricious manner

X с жиру бесится = it's X's plushy (cushy) life that makes him act so fussy (behave capriciously, act like this etc )

X doesn't know when hefc well off X is too well off for his own good X does what he does for want of anything better to do.

(author's usage) (Старый повар:) Вишь, черти проклятые! С жиру-то! Черти!.. (Толстой 3). (Old Cook:) See what the damned devils have done! It's their plushy life that makes them do this. The devils! (3a).

Андрей натянуто рассмеялся: «Сейчас она скажет: вы ублюдки, с жиру беситесь». — «Вы ублюдки, — сказала Таня. - Я ваших заумностей не понимаю, а с жиру вы точно беситесь» (Аксёнов 7). Andrei gave a forced laugh and said, "Just you watch. Now shell tell us we're a pack of animals and don't know when we're well off." "Well, you are a pack of animals," Tanya said, "and even if I don't understand all the ins and outs of your politics, I can tell you don't know when you're well off" (7a).