What it will be, how big it will get, how profitable it will be depends on you. A domain is your ticket to dreaming and achieving big things. Start from the assumption that there are lots of sharks on the Internet. More people want to be on the Internet with their own domain than understand how to achieve that objective. Knowing this, some people with advanced technical skills but without moral grounding take full advantage of this fact to fleece the newbies.
Many newbies think that by registering a name, they get a domain.
Domains are provided by Internet Service Providers who are actually renting you a portion of space on their server. Quickly you'll find any hope of profit evaporating. This is why you've got to go with a reputable company, to ensure that you're not confused and taken in by things like these. You're told you need 150 megabytes of space with your domain. One way ISPs take advantage of the unsuspecting is by offering them more space than they need.