Last night, the blockchain was a bit congested. I was watching that transaction queue in the mempool, feeling like a delivery rider circling at the door... Clicking "Send" is actually just throwing the order into the waiting room: first checking if the gas price is high enough, if not, slowly moving it back; in the meantime, it might be cut in line by someone offering a higher bid (to put it simply, you think you're running, but you're actually standing still). What's more annoying is that if the tools or tagging systems you're using update slowly or are misled, the "confirmed/safe" notification might also lag behind, creating a big psychological gap. A friend also asked me, "Isn't it just a click to get on the chain?" I could only say: theoretically yes, but during congestion, don't be too confident. It's better to operate less and change parameters less; if it fails, just consider it a tuition fee.