Nah.  When I first heard about bitcoin back in 2012 or so, I assumed it was some sort of scam--or at best a fad or gimmick like Flooz was in 1999, some sort of internet currency that nobody wanted or needed and that would die out within months.  Turns out that I never changed my position on the latter (I think it's a solution in need of a real problem, at least for civilized countries), but I was dead wrong on the first part.  It's definitely not a scam, Ponzi, pyramid, or otherwise and it took off to a degree beyond anything I'd anticipated.

Right now I'd be careful investing in it, because it's near its all-time high, and that's exactly the point at which people start inflating the bubble and then it pops.  Can't say for sure if or when that's gonna happen, but I get the feeling that it will.  We'll see.  But it's not a scam.