Is that Musk's first time holding a gun? What a bunch of bizarre decisions. Bipod and monopod down. No sights. Hip firing a sniper rifle. Wrist angle is really bad for a .50.
The Barrett isn’t really meant to be a serious gun for consumers. It’s a gun you rent while closing your eyes to swipe your credit card, then do stupid shit like hip firing or dual wielding.
It's like one of those crazy expensive ultralight racing bikes: it makes a difference for pros and a few very good amateurs, but the vast majority of people who own one have it purely as a status symbol.
Even then, the barret isn't even that good if your goal is distance. Gotta go with that sweet sweet .338 Lapua or .408 Cheytac. If he's gonna larp he may as well do it right
IIRC he did it because someone said on Twitter that hip firing a Barrett doesn't make sense, and Musk went "Oh yeah, but what if you're hecking epic like me tho?".