I know this will sound inconceivable to you but some people genuinely think nobody should have that much money - including themselves. If you want to make it sound irrational and emotional the correct word wouldn't be "envy" - it would be "fremdschämen" or if you prefer something not borrowed from German: "cringe".

This is the weakest retort to critique of the wealthy. "Youre just jealous". Lame.