It's not so much dangerous if you have a computer dedicated to it, but you'd need to spend quite a bit of money if you want it reliable.
You'd need a computer, but with a great deal of RAM. You also need an extremely fast connection [a
dedicated 100mbps port, separate from the one you browse with, or a 1gbps port], you need a UPS setup, cooling systems, etc.
Apart from hardware, you also need knowledge of server software such as Apache or IIS, and knowing a few web development languages wouldn't hurt. On top of that, you need to worry about security and how to handle errors and protect against things such as DDOS attacks.
Unless if you're really into it and have a solid mindset that hosting it yourself is both needed and worth it; I say stick to hosting providers.
EDIT: Oh, and did I mention you'll need to be paying for a DDNS domain in order to link your site to your IP, as well as paying your ISP extra for a permanently static IP?