$50/week in allowance isn't that much. Working part time as a manager at Sonic I earned $200/week.
If a parent makes $60,000, which is simply upper middle class, they're making about $1150 every week. If Glass is an only child it's perfectly reasonable that he gets $50 of that a week in allowance.
And it's also completely credible that he's spent half a year's allowance on Blockland keys that he can get banned from the forum with.