It's not normally at the top of most DIYer's lists to install a gas line in their home, but every once in a while, the time will come when you'll need to do some kind of maintenance work. When that time comes, and especially if you need a whole new line replacement, you should absolutely hire a professional gas line installation contractor for the reasons outlined below.
It's Illegal to Do It Yourself
Gas lines, no matter how long you plan on installing it, need to be installed by someone who is licensed and carries insurance. It should go without saying, but installing a gas line is a very dangerous job. Even if it doesn't explode, it can still leak gas into your home, which can be fatal. Moreover, in some jurisdictions, it's actually against the law to perform a gas line installation yourself, so you're taking numerous risks to do a job that can - and should - be done by a professional.
Professionals Have Experience
One of the biggest mistakes any DIYer makes on any project is assuming that they can just "figure it out" along the way. In reality, one of the biggest dangers is not knowing what you don't know. Licensed plumbers have the experience to be able to know exactly what needs to take place and when. In short, they can see things that you can't. Installing a gas line, for instance, is not as simple as just hooking up a few copper pipes. You have to make sure the line is sized right to match whatever appliance you're wanting to install, as well as any other future projects you may have in mind. Incorrectly judging something like this can lead to major headaches down the road for you and your family.
Protect Your Other Assets
Appliances are not cheap, and some DIYers believe they can save money on the back end by doing the install themselves, including running new utility lines. While it may look simple enough, incorrectly installing gas lines can not only be dangerous - as outlined above - but can also damage your new appliance. Professionals know how to not only perform a gas line installation, but they can also hook up your existing appliances to it. They also carry insurance (always check before you hire them), which will protect them and especially you in the event that something goes wrong with the install.