These people may have not been wrong, just early. Keep inflating a balloon - it's hard to say when it's going to pop, but still accurate to say that it will at some point.

If I had money invested in bitcoin, I would pursue a strategy that kept in mind that it very well could be a bubble- and one that could lose most of it's value before you have a chance to get out.

The wisest plays aren't the ones that make the most money, but the ones that concrete gains by taking the profit off of the table: Sell out X% every time it hits a new arbitrary high.