Recently, people keep asking me, "Should retail investors understand block builders, bundles, and these concepts?"

I think, knowing just that "it will affect your transactions" is enough: when you click confirm, the transaction may not go directly into a block; it could be bundled, reordered, or even front-run.
Don't bother memorizing a bunch of abbreviations—remember two things: don't set your slippage too high, and don't chase market orders in low-liquidity situations.
Use reliable RPCs/wallets whenever possible, at least to avoid putting yourself at risk of becoming just a target.

Do you need to study enough to draw flowcharts?
No, unless you're actually doing arbitrage or running nodes.

Also, these days, everyone is talking about rate cut expectations, the dollar index, and risk assets acting wild together...
When the market gets volatile, more people are "snatching positions" on-chain, and the presence of bundles and similar concepts will feel more prominent.
Anyway, after watching nodes for a long time, I can say: no matter how complex the mechanism, it ultimately comes down to incentives.
Don’t assume others will "play fair."