For someone with big aspirations of his own, Elon Musk doesn't seem to be as supportive of other people's outlandish goals. 

The Tesla (TSLA) , SpaceX and Boring Company CEO took to Twitter to deride Uber's plans to build a fleet of flying air taxis after being asked a question by journalist Anirban Ghoshal on behalf of Uber CEO Dara Khosrowshahi. 

New @Uber CEO @dkhos says why do you need to dig tunnels for @HyperloopOne @hyperlooptt when you can fly? Challenges @elonmusk what do you say to that sir @elonmusk @vccircle @vccstartups pic.twitter.com/Mu0GyPIaSI

— Anirban Ghoshal (@journoanirban) February 22, 2018

Instead of being solutions-oriented, Musk replied with snark to a suggestion that flying taxis would be a more practical alternative to his idea of building underground tunnels for his Hyperloop projects. 

Being the competitive person he is, Khosrowshahi took Musk's derision as a challenge. 

Challenge accepted. Improved battery tech (thx 2 @elonmusk) and multiple smaller rotors will be much more efficient and avoid noise + environmental pollution. https://t.co/563U0RqDYF

— dara khosrowshahi (@dkhos) February 22, 2018

Musk is on a high after his Hyperloop company received a permit for the preparation and preliminary excavation of a site in Washington D.C. 

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