He only knows how to do one thing.
If a client wants a web site, he farms it out, then adds a mark up. If a client wants a Flash banner, he farms that out. Logo design, farms it out.
Now if he were super busy all the time, then it's a great way to make a living... don't do the work yourself and make money on other people's talents. Hey large agencies do that all the time. But you want to be a successful freelancer so you have to have many areas where you can make a profit.
But getting back to this freelancer that I know... he's NOT busy all the time. And instead of earning $5000 on a web site, he earns $500.
As a freelancer, you have to open up different revenue streams and to do that you should know how to design for the web, do animations, retouch photos, design logos, brochures, sales promotion material, and all sorts of other collateral material as well.
When a project comes in, I handle it ALL. This is a win-win for my clients and for me.
1- When they see my portfolio on line (www.digitalartist.com) they want ME to work on their project... not someone else.
2-I can offer a very competitive cost for doing the project for my clients because I don't pay anyone else to do the work for me (that I would then have to mark-up to cover the time I spend overseeing the project).
3-I can get a fair and reasonable fee for my work.
Bottom line... the more you can do for you and your client, the more successful you will be as a freelance graphic designer!