One thing I might point out is that exchanges have no risk since they simply provide the platform; their risk is low and their profits come from commissions. Liquidity providers, or market makers as they've traditionally been called, bear the risk, and make money off the spreads - not an easy business as anyone who's worked in NY or Chicago will attest. So, when referring to "liquidity providers" it's good to keep in mind that this is a risk what you can afford to lose venture ... and more so when entrusting the job to others, or worse yet, algos.