I kinda think that was Max's reaction the first time Bart did it. Which is a good thing.To use an example, there was an early Impulse comic where Mark Waid had Bart drive a car off of a cliff. And it was funny, because the entire book was funny. The world of the Impulse comic was one where things usually didn't have to be taken seriously. Fast forward to the Teen Titans series, which had spent the first few issues showing just how serious it was going to be. Then Geoff Johns had Bart drive a Batmobile off of a cliff. My reaction wasn't "This is funny", it was "Bart's recklessness is going to kill everyone".
Though I absolutely did find it funny, it absolutely was the sort of thing that could get someone killed and Bart did a lot of things that could get someone killed (treating the world like a video game to a degree) and learning to not do those things was kinda the point. There was tons of that sort of thing in Impulse. He absolutely could be serious at times (Preston shot (grazed), Max in hospital, Arrowette hostage). Totally buyable, but he he needed to learn when to apply that. Him growing up is good. And yes, he was always going to have to learn when to take work seriously. But I am not interested in the personality-rewrite versions of that group of characters - some more than others just had new personalities pasted on (sometimes with horrible things to make it happen) and some were definitely not improvements.