actually, it's entirely possible. i know of prop trading groups that have been around for ten years with only one or two down months.

in dislocated markets, making markets is actually relatively easy, so it's not that surprising that they usually don't lose money. they also have hundreds of traders. each one of them probably had many losing days, but in aggregate, they have good traders and systems, so they rarely have losing days now.

also, how do you know that it's impossible without insider information? what reason do you have to back up your claim?