In today's dynamic conditions, it's very difficult to collect the people you know into one safe place. It's certainly not Facebook, and probably not LinkedIn. Years ago I tamed Outlook to my will, so I tend to collect things there. In the long run though, none of these will suffice. So until our "personal data locker" is ready, we have to find away to safeguard our connections. 

The GMail Consolidation

I recommend opening a special GMail account for yourself. You can import Outlook and LinkedIn contacts easily. I fetched my Facebook contacts through a Yahoo account, because Yahoo mail accounts can import Facebook connections. The free Contacts feature of GMail will attempt to merge duplicate records, and where it cannot, you'll probably see the records listed next to each for easy usage. The Outlook CSV format seems to go every where easily. 

Emails only?

At the free account level, about all you are getting are email addresses. But if your keeping more complete account records in Outlook, GMail or LinkedIn, you'll either get some automatic merging, and the data will be easy to merge. 

Extra security

Finally, once you think everything's in GMail, export that data and store it in a couple of different places. Now you have a reasonable chance of keeping your connections, even if you get de-friended or worse, locked out of an account. It could happen!

Want to do it yourself?

If you need more assistance in following this procedure, please comment and let me know about your knowledge level. I don't have time to do it for you, but if you can share your issues, I'll get you moving in the right direction.