Here's a good way to think about this.

If I have a business and I raise $10M at a $100M valuation for 10% of the company, the people giving me the money really value the business at $90M, their addition of the $10M into the business brings the valuation to $100M.

It's not always exactly like that, 1 for 1, but that's the gist. Without the capital, the business is not worth as much as the valuation at the time of the raise.