Last night before bed, I was browsing on the chain and saw a swap that looked like a "decent spread" to me.

Upon closer inspection, it was actually a sandwich: someone bit first to push the price up, and when I go in, I end up paying the fee for someone else...
Honestly, the opportunity might not be yours; it could just be someone else collecting tolls in line.

Arbitrage is similar; the small profit on the chart is often reserved for bots, and ordinary people who are a second slow only get slippage and emotional losses.
Recently, looking at the inflation + studio + coin price spiral collapse points in blockchain games, the logic is the same: you think you're "playing to earn," but in the end, you might just be feeding liquidity into the system.
Anyway, when I encounter uncertainty now, I prefer not to place an order, treat that money as if I didn't see it, and go to sleep.