Despite not having been tagged in the post, McIlroy replied directly with a screenshot of his enviable record, saying "More like 200mill... not bad for a "bored" 28 year old... plenty more where that came from".
Elkington also claimed McIlroy was happy enough with four majors and "100 million in the bank".
McIlroy's attempt to add to his haul of four major championships at Erin Hills ended in the world number two surprisingly failing to make the weekend in Wisconsin.
Elkington was watching the U.S. Open before he made a backhanded compliment about McIlroy. Jack won 18 and never mentioned his total cash.
Juventus considering approach for Donnarumma
Owner Li Yonghong wants Donnarumma punished and benched for a year, but this would force Milan to give the 18-year-old for free. Milan CEO Marco Fassone revealed Donnarumma's decision to leave the club earlier this week.
McIlroy has revealed that he intends to play in next week's Travelers Championship and the Irish Open, Scottish Open and Open Championship in successive weeks in July.
"I missed the cut, but I'm optimistic going forward".
For the first time since the world rankings were introduced in 1986, the top three all missed the cut - with Dustin Johnson and Jason Day sharing McIlroy's fate.
You had to go down to newly-crowned Masters champion Sergio Garcia and double Major victor Martin Kaymer - both in a share of 19th place on three under - to find the first players who already know what it is like to lift one of the game's biggest trophies.