What ever makes you fall asleep. And the scripting in Roblox doesn't seam so Childish considering only a couple people got it mastered. It wouldn't be such a childs game if it weren't for the "Children" who play it.
For one, they are a company and moderate with bots.
Second, their demographic is around 5-10.
Thirdly and most importantly, as a company, they advertise.
Blockland is an indie game and therefore is not capable of carrying out advertizing to it's fullest ability. However, at the rate of increase of BL_ID's, I expect 30k's to roll in in under 2 months, 40k's at around March-May 2012, 50k's at around February-May 2013, and 60k's at about 2014-January 2015.
In Short, it's gonna be a while and there is really no way to predict accuratly when the new ID's will hit. I made an estimation, or educated guess.
It took 1 month for 14k's (My Generation woot), 2 months for 15 and 16k's, about 1 month for 17k's, (at the start of summer vacation), the 18k's about 3 weeks, the 19k's about 6 weeks, the 20k's around 9 weeks, (school starts around now) the 21k's around 1 month, and then the 22 and 23k's about 4 months. After this I stopped counting.
There is always an increase at the start of summer and a smaller boost at Christmas.