Is it possible to make xyz.com or a site like Facebook with Drupal?
Is it possible to make xyz.com or a site like Facebook or any other combination of name and currently existing application with Drupal?
The answer is yes. Just take a look at the hundreds of thousands of results on Google for that same question. So, eager web site desirees of the world please stop asking that question. Yes, it is possible. The real question is, can I do it, and if not how much is it going to cost for me to pay someone else to do it. These are the right questions. Even with all the free time in the world, you will not able to create Facebook. That would take a team of people. Facebook has employees in the thousands and money to spend on the equipment and expertise it needs.
If you are asking this question, you most likely don't have these things. So scale back and ask yourself, what are you trying to accomplish? Is it a business goal? If so, treat it like a business decision, you need to pay people in order to produce a product. Find great talent and you might produce a great product, perhaps even the next big hit. However, it's not going to be easy, and it's probably not going to be cheap. Take a look at some other attempts at creating online social network websites (cause this is what most people really are trying to ask if they can build). Even low-key sites can run into the tens of thousands of dollars. Especially, if you don't scale down your requirements and goals. Always think first about your goal, then decide how to get there. Do not worry if it can be done. Oh, and I've had experience on some startups now so feel free to contact me if you are interested in building a website. ;)