Audiences were totally consumed floating in the euphoric feel-good cloud that was E.T. the Extra-Terrestrial when The Thing hit theaters two weeks later. They just weren't in the mood for something that was about as far as you could get from puppies, rainbows, and cute aliens.
Looks like Fathom will be bringing The Thing back to theaters next month for its 40th anniversary. FORTY YEARS!!!
https://bloody-disgusting.com/movie/3715991/fathom-events-bringing-carpenters-the-thing-back-to-theaters-for-40th-anniversary-in-june/