Recently, I keep seeing people treat "block builders" and "bundles" as new mysticism.

In fact, retail investors only need to understand to what extent: you have to realize that the transactions you send out may not be included in blocks in the order you want;
someone might bundle, cut in line, or sandwich your transaction. Especially those who chase hot topics, have large slippage, and love using market orders, are the easiest to be manipulated.
As for how auctions work at a deeper level, or who collaborates with whom... honestly, it doesn't matter much to me. I also don't plan to be a hunter.

I also glance at large transfers on-chain and the movements of hot and cold wallets on exchanges, but now it’s increasingly like an amplifier of emotions:
people say "smart money is coming/going," while they get themselves all itchy and anxious.
My approach remains the same: dollar-cost averaging + rebalancing, try to use limit orders, don’t chase that one spike, and if there’s on-chain interaction, think through slippage and gas carefully.
If possible, split into batches.

What I’ve learned isn’t tricks, but rather not to put myself into someone else’s pre-written script.