This is similar to Pete and Joe's answers but I wanted to add a little detail to explain why it's a terrible idea to pull money out of your investments for something like this. I found this site the other day and it's really helpful, I think, to get your head around opportunity cost. You should play around with it but let's talk about the yearly return of the S&P 500 (a proxy for the market) over last 5 years:
Is 2018 going to be like 2013 or like 2015? No one knows. Now consider that the market doesn't just increase day by day. Look here at 2013. On 10/19 it was at $1656.99 on the 22nd, it was 1754.67. That's 5% over the course of 3 days. What's your credit card charging you? Let's say it's as high as 25%. That's about 2% a month.
The problem is that you don't know when these jumps are coming. You pull the money out and you miss the 'opportunity'. While you are making income, you should really not be taking any money out unless it's really necessary. Even if you put the money back, you could regret taking it out.
Now, I'm not saying you should use buy things on credit. Only buy things you can afford. But I also believe life is for the living. If you have no debt and you have savings, there's nothing wrong with getting yourself something once in a while.
Addressing the following statement from a comment:
"it is better to liquidate investments than use credit cards"
This a very wrong misconception about investing and a huge mistake that can destroy your returns.
Let's say you need to fix your car, and you don't have the $1000 in cash but you need to get to your job so you can get money to pay for it. You can either liquidate some investments or use a credit card and pay for 2 months of 18% interest ($30). You should absolutely use the credit card and leave your investments alone. The CAGR of the S&P is around 10% historically but most of that growth comes from big jumps over short term time frames. In other words, in order to get that long term growth, you need to be in the market the whole time. The market routinely grows 10-25% over 2 months or $100-$250 in this example.
Of course, you could get lucky and the market could drop significantly over the same time or not really move a lot. But no one knows which it will be. The reasons this is a bad idea is the same as why market timing is a bad idea.