I would hope that the answer to that is obvious, but these days so many people have access to excellent cameras, so why not just do it yourself?
Well, sadly, not everyone who calls him or herself a professional photographer really deserves the title. And when comparing the work of that kind of "fauxtographer", yeah, you might as well do it yourself. Many newcomers, part-timers, and "friends with a nice camera" don't realize that a LOT of time, effort and ability goes into the kind of quality an expert can do and be able to charge professional prices for. Those clients who appreciate quality will gladly invest in portraiture that they will be proud to own for their lifetimes.
As to doing it yourself, I gladly accept the challenge to continually produce work like this that makes it obvious as to why we charge what we do.