When you bet against house with good odds to beat it (sports betting, blackjack, but not, for example, roulette or this mempool madness), don't see anybody being hurt. Even when I lose I don't feel hurt, as I usually do analysis aftermath and mostly came to conclusion that I still did correct risk / reward calculations, just luck wasn't on my side this time. And also betting vs individuals is ok, just try to be sure that both parties understand what they are doing. Also betting is good at predicting future, as people think twice with their predictions when money is involved.