Sam's an introvert, any sustained mode of extroversion on demand wears on him badly. Fishtank is the only time the public is able to witness it, though, because when you're a running a show, you can't escape for a week to recharge your batteries playing Skyrim or Starfield 100 hours straight and then return with newfound monomania. Any downer day with any annoyance has a way of tilting one's decision making in a way that's bound to culminate in boiling over in a radical way towards perceived release.
Sam throwing rice and breaking the TV had the same energy as when he slammed doors and yelled at Jimmy for failure to perform. Like 25% more insane than the occasion should have him. Worn thin, extra tilted, burning it down. Post-reveal, his mood was apologetic, 25% more explanatory than circumstances should have him. Post tilt clarity, salvage mode.