Lately I keep hearing people talk about blockchain builders, bundles, MEV and so on.

Honestly, retail investors don't need to memorize a concept encyclopedia; knowing two things is enough:
First, when you click "swap" on the chain, the transaction may not execute along the path you see; it's normal for someone to bundle, cut in line, or even sandwich you.
Second, what you can actually do is quite limited—use reliable routing/aggregation tools, don't be greedy with slippage, avoid rushing during low liquidity, split large orders, and if possible, use private transactions (at least to reduce being targeted).

I used to be quite stubborn, "I only look at on-chain data," thinking on-chain info was crystal clear, but I later realized I could be fooled myself: seeing a price difference in a pool, jumping in only to find the bundle has already eaten the liquidity, and I was just filling the tail… Forget it, just accept that I’m a lone wolf small fish.
Recently, RWA and comparing on-chain yields with US Treasury yields are also quite popular.
My feeling is, don’t just focus on APY; the friction and slippage during trade execution, the losses from being sandwiched, are more damaging over time than you think.
First, cut down unnecessary losses, then talk about returns.