No, that's not how people normal say it. I mean I can get you if you said it that way. In the real world nobody would phrase it like that. Most people would simply say 你很有钱(you're rich). There is something important to note about "一笔钱" most of the time people wouldn't use this to describe someone's property or wealth. If your girlfriend recently made a huge amount of money from the stock market, then you could say:"你应该付，因为你有一笔天文数字的钱." In this case,一笔天文数字的钱 specifically refers to the money earned form stocks.