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I have, quite a bit, two decades ago. I came to the conclusion that's it's a suckers game and decided never to do it again.

There are basically two ways one can win at it:

  1. "It's a gamble, use gut feeling, enjoy the thrill but box your risk carefully" - if you do it for a while and manage to stop you can get off on top.
  2. "You have priority access to privileged information" - then if you implement correctly you should be able to win big.

But otherwise (no priority access to privileged info AND not keeping in mind the huge risk at all times) you're going to get wrecked, sooner or later (mathematically)

This is what has kept me away from it, as I have seen and heard of many more getting wrecked. I am also not bright enough to keep up with all the information needed to play these games :)