1. What arbitrage really is
Buying an asset on exchange A and simultaneously selling on B where the price is higher - risk-free profit if both legs execute simultaneously. That "if" is the entire story. True arbitrage is a technology competition: colocated servers, private order flow, API rate priority, pre-funded accounts on both venues. It exists. It is not accessible to you, and that is fine - knowing why is the lesson.
2. Why the gap you see is already gone
Public screens update in milliseconds; your round-trip takes minutes (order placement, confirmation). The participants who profit from price gaps are bots that (a) see the same gap in microseconds, (b) trade pre-funded on both venues, (c) pay maker fees or none. What remains for a retail trader clicking a web interface is the gap after those participants took it - usually smaller than the combined fees.
3. The hidden costs that eat the "free money"
Fees on both legs (0.1-0.6% each), the withdrawal fee, and - the structural killer - transfer time: moving 0.1 BTC between exchanges takes minutes to hours, during which the gap can close, widen, or reverse. Capital is trapped in transit on both sides. Slippage on the larger leg scales with size. And the "risk-free" label quietly assumes both venues honor withdrawals in that moment - see FTX for what happens when one leg can't.
Remember: A persistent price gap between two exchanges is usually not free money - it is a warning label: one of the two prices is hard to exit at, or the venue carries a risk premium.
4. The premium that means danger
When an asset trades 5-20% higher on exchange A than on B for days, the market is pricing a risk: withdrawal suspension, delisting, insolvency suspicion, or a country-block making one venue the only exit. Buying "the discount" means buying the risk. The Korean "kimchi premium" and USDT-discount episodes during bank runs were precisely this: risk premiums wearing arbitrage costumes.
5. When this fails
Arbitrage fails for retail in every dimension simultaneously: execution (both legs must fill - slippage on each), timing (transfer latency), cost (fees twice + withdrawal), and counterparty (the cheap venue is cheap for a reason). Bots and automation promise to fix this; they scale the competition, not your advantage - see Bots and automation.
Risk: Every "arbitrage opportunity" sold in a Telegram group is either stale, a honeypot, or the front end of a deposit scam. Real arbitrage desks do not recruit via DM.