It benefits the company during the initial public offering (IPO) and anytime they release more stock after the IPO. The company also owns shares of it's own stock which it can sell to raise funds. This is a large funding method for any publically traded company.
Buying non IPO stock or not buying newly created shares does not benefit the company in anyway.
If you went out and bought 1000 shares of Apple stock today the company would not get any additional funding because you are not buying the shares from the company, but instead you're buying the shares from other investors who are looking to sell their shares.