I personally think the posters on this site generally espouse what I would characterize as a "weak tight" approach to BR. Having 500 BB on hand for a game is completely ridiculous unless you're barely a winner at all. Even 300 BB is usually excessive, because for every good player that goes through a 300 BB downswing, there are many who never experience it. It is true that if you play poker long enough you will go through a 300 BB downswing, though everyone here seems to think this means it is somehow likely to happen to a given winning player in his lifetime. It isn't.

Many (not all) of the posts on here from "established" winners who have gone through lengthy downswings are, I believe, from people who are marginal winners with significant leaks in their game that get magnified by the frustration of a downswing. If you're a smart player, are more than a marginal winner (2+ at least), and if you can actually handle a 100 BB downswing without tilting away another 50 BB, you're highly unlikely to experience a 300 BB downswing in your lifetime. So relax about these doomsday BR requirements and play solid poker.