As part of Stellar's marketing strategy they are giving Lumens to anyone that owned bitcoins prior to the 26th of June 2017. I've just claimed mine. Here's a link to the Stellar blog post explaining how to do it: https://www.stellar.org/blog/why-btc-giveaway/
Currently each Bitcoin you hold is worth about $18 at the time of writing. But be quick. This giveaway ends on the 27th of August so don't mess about!
Why wouldn't you claim it?! And once you've claimed it you can transfer them into your own wallet or onto an exchange like and do whatever you want with them. If you have any questions or issues with the claim process, leave a comment and I'll try and answer it.
Great