Various outlets have reported that Google+ traffic fell by 3 percent last week compared to the week prior. Average time spent there was down by 10 percent.

Here’s why this is happening:

More than 500 million people already have a social media home, and it’s called Facebook.

Many have years invested there. Hundreds of relationships. Countless photos and albums. Thousands of comments, messages, and “likes.” Facebook is a social media home for a critical mass of mainstream consumers.

Google+ is asking people to move homes, only there’s no way to really pack up your belongings at the old house  — along with your friends and neighbors in the area — to move them to the new house.

Plus, people’s friends don’t really hang out in this new neighborhood called Google+.

People aren’t currently changing social media homes.

Maybe you’re thinking: but wasn’t Facebook successful in getting people to switch from MySpace years ago? 

Eventually. But if you recall, there was quite a bit of time that Facebook brought in people who were not on Myspace. Adults, rather than kids and teenagers, flocked to Facebook. Eventually the kids came over too.

Now, for the launch of Google+, everyone is on Facebook. It’s going to be very difficult — damn near impossible — for Google to convince a critical mass of consumers to leave Facebook for its social network. (That’s the decision. One or the other. Most people don’t understand the point of maintaining both.)

It’s the same for all technologies, if somewhat less dramatic:

Once somebody develops an affinity for Android devices, or iOS devices, that is mostly where they stay. If the product is being aggressively developed, and marketing is excellent (as it is in both of these smart phone / tablet cases), people fight for their home products.

Barnes & Noble will have a very difficult time getting Kindle loyalists to switch to the Nook. Amazon is these people’s home. That’s where their book collections live.

Same with Netflix. For all the uproar over pricing, people still love the Netflix service. It’s a good home. What’s better?

And so, Google must convince people that its Facebook alternative is not only better, not only worth people’s time, but worth people’s loss. The loss they will perceive when they lose their current (social media) home. It’s hell of a task.