Do you think that once you click send, the transaction is immediately "on the chain"?

Actually, many times it first queues in the mempool, competing with a bunch of others for miners/validators to pick, the more congested the more you look at the fee: if you set it too low, you'll be left waiting; if you set it high, you might get stuck in the middle, bouncing back and forth, or even expire after a long wait, and you might still end up paying some gas. Recently, with meme attention cycles coming and going, the chain suddenly feels like rush hour, and veteran players advise newcomers not to take the last step—I really agree with that... I now prefer to check the congestion first before deciding whether to rush in; anyway, missing those few seconds isn't a big deal.