I've been working toward it for a while, but I finally hit the gold level of 75k before the 50k gold level. The significance is that the highest score is so random, and relying on a high score as feedback for good play is not enough. What is important is a high average, a consistently high score each time you play.
When looking at people's scores you can usually distinguish a bubble around a certain point (wins in each 25K bracket slowly increasing until falling away). Increasing that bubble point is more important than waiting on a massive score to land in your lap. Of course the more efficient you are, the more likely you are to take advantage of a lucky streak.
With each iteration of the game, the average scores have slowly increased. Initially it was almost impossible to land a 250K+ score, but now with the instant moving and bonus gems it's possible to get a 250K each week, and a 500K+ score to get onto the top of the friends list. This makes it hard to read exactly where long time players are at, but at least the stats are now visible. What I'd like would be a simple way to map your own graph against someone else's, or a way to compare your stats this month against last month to give a better indication of progression.