Sucks for Haliburton and the Pacers, but the risk of further injury was definitely worth the reward of a championship. Who knows if Haliburton will ever get back to the Finals and be one game away from winning a championship again. This is what you play for, and you're too close to not try to play through injury if you're able to, and Haliburton was playing very well for over a game with a strained calf before the achilles. Dude also already has his bag, so he's set for life either way.
Edit: NHL players have all sorts of injuries that come out after they're eliminated in the playoffs, or win the cup. Look at the injury to Matthew Tkachuk. He probably shouldn't have been playing in the playoffs either, but we celebrate how much of a warrior he is by playing through it and winning the cup.