Out of all the money I make, some goes to necessities, some goes to charity, some goes to fun and entertainment and the rest I invest back into my business. I don't think that it takes money to make money because I have made money out of nothing. But the money I do make I like to put some of it back into whatever project that has made me money. If it works then why not spend it on making it work bigger and better?
This method is highly effective because not only you're not losing any money in the process but you always have money coming in. The more you put into it, the more comes out. If you have a Facebook page that's promoting a product and you're earning sales from that page, you can use some of that money to run an ad campaign. You can also spend money on Google Adwords and Bing Ads as well. Test things out and see what works and what doesn't. Once you find something that does work, you can invest your earnings in that so you can keep the money coming in.
All professional businessmen have been using this tactic because it works. It's good to get in the habit of spending money on your business because money is a tool. You can use money to make more money. Have your money work FOR you instead of working for it.