What makes you think it's a bubble? It's gone from over 1000-ish to 9000-ish a few times the past couple of weeks and always bounced back. Seems silly to sell now imo, unless you're doing day trades.
Compare the current price to the price a year ago. And now tell me what has changed since. What?
The number of transactions has only gone up by about 70% since. It isnt even used twice as much as last year, but the price has climbed nearly hundred fold.
So, what has happened? Is bitcoin more usefull than last year? The only thing that has changed since is awareness, it has been been in the press a lot, sure.
The value as a transaction medium hasnt increased significantly, but the price has skyrocketed.
So, i think it should rather ask you what makes you think this isnt a bubble?