You might notice that the prices of trading A for B, then B for C, then C for A results in more A than you began with if done instantaneously.
But you can’t do that for a trillion dollars, because the “price” of an asset is just the best offer to buy or sell, and those are capped at the quantity of the best offer. Once you exhaust those, the arbitrage might not exist anymore because the remaining best offers will be worse. Say the market has capacity to actively exploit arbitrage for $10,000. You will earn the same amount of dollars if you have $1,000,000 or $10,000 if you exploit it to the max, but your return will be 100x better if your base is $10,000.
But you can’t do that for a trillion dollars, because the “price” of an asset is just the best offer to buy or sell, and those are capped at the quantity of the best offer. Once you exhaust those, the arbitrage might not exist anymore because the remaining best offers will be worse. Say the market has capacity to actively exploit arbitrage for $10,000. You will earn the same amount of dollars if you have $1,000,000 or $10,000 if you exploit it to the max, but your return will be 100x better if your base is $10,000.