Market Makers

[Sand87]

How do these people operate? They're there in every single market it seems. Do they calculate their own odds for every single market they enter and then put higher odds up and just wait to get matched? Or do they just put up odds that they know are far too high and accept any bets down to a minimum and then get out? You see their bots all the time with something like 200 on the back side and 205 on the lay side. If both got matched then there's profit but what happens if someone takes all the money available to back and the price drops? They are then left with a lay that they can't get out of unless it's for a loss. Or have they priced things up so accurately that they can afford for this to happen, safe in the knowledge that they layed at lower than was value anyway? So many questions!! Also, how can you compete with them? They always act like bookends, sticking up large amounts on both sides with only a tick inbetween, effectively blocking everyone else from getting another price.