Front-running is fine with me. It I place a limit order that says I'll buy a pizza for $10 or less, and someone can buy that pizza for $8 and sell it to me for

Front-running is fine with me. It I place a limit order that says I'll buy a pizza for $10 or less, and someone can buy that pizza for $8 and sell it to me for $10, I'm a happy buyer -- I'll expect to get at least $10 of utility out of that pizza. Without funding the market-makers, there may be no market....