First of all, an artificial tree is a lot easier to maintain. It doesn't need any water, fertilizer or sunlight – all it need is to be cleaned once in a while.
An artificial tree does not need to be cut down as it will always stay the same size. We all know how normal trees can overgrow your home and create undesired shadows. Something like that will not happen with an artificial tree.
Artificial trees can be planted everywhere. The climate doesn't matter, you can have palm trees in Alaska if you want it (although it might look a bit out of this world).
There will be no problem with insects and other animals. You really have to be unlucky before your artificial tree becomes the nest of a disgusting bug colony.
Finally, you can easily move your tree around if its not to big or even pack it away for a few months. People bringing their trees with them when they move are not unheard of.
Most artificial tree look very life like, but for the ultimate experience it might be desirable to go for a preserved tree. While artificial trees are normally made of plastic, a preserved tree is made of natural materials around an empty trunk. The natural materials will even make the artificial tree smell the right way.
