thought cross-exchange arbitrage was free money… here's why you barely make anything (review)

exchange A pricier than B? just buy cheap, move it, sell dear — free, right? reality: ① the gap closes while you transfer (transit time) ② withdrawal + network fees ③ fees on both sides ④ slippage if the book is thin. after all that there's almost nothing left, or it's negative. it's basically a fee war, so having a rebate at least defends the margin. not worth the time at small size