There are a few reasons to do this:

1) To control your reputation management better. Perfect example is on this link: Ron Ianieri. Look at the name you are clicking on and then look at the domain name you arrive at. Someone else snagged up this domain before he did and it is not to his advantage.

2) Search engine rankings. If someone is searching your name, having your name in the domain is an added bonus to ranking well.

3) Promotional quality. It’s (usually) easier to tell someone your domain is myfirstnamelastname (dot) com than some clever word play, like net experienced. ;)

4) Mistaken identity. If someone goes to michaelshearer.com they’ll see it’s a crappy, undeveloped geocities site. They might think, “hey, this guy Michael Shearer is a web developer and internet marketer but his domain is lame!” It’s not my domain and I’ve already tried to acquire it to no avail. I think he misspelled his email on his domain registry. Also, you might get famous so you want to be ahead of the game. Now, if I become famous, michaelshearer.com will probably cost me much more than if I try to buy it from the owner now, as an ordinary guy.