Don't the 'high-roller' tables have a higher minimum bet? Most people don't start out at the $1 table, and then move up to the high-roller table as they keep losing though. Most people just plop down at a table that has a range/minimum that is right up their alley with regards to their average bet. Then they only really move if there is a reason to (like feeling that this table isn't 'lucky' anymore, or the dealer changes, etc).
But now that I think about it, you could always just move to another table with a higher limit. Of course, if you're going through all this trouble to make $50, you probably don't have the bankroll to keep going.
Maybe another reason for tables having different limits is that the pit bosses don't trust the dealers (or security?) in the low-roller areas to handle money above a certain amount?