I did this trade last year - the risk in this trade is the cost of the roll waiting for the spike in vol. The trick is to find a way to reduce your cost basis each month. I sold ~15 delta VXX puts to offset the /VX drag (I'm sure there are other ways to reduce your cost basis, but this was how I did it). So if the spot is at 12, you are selling 11 VXX puts. It doesn't perfectly cover your roll cost month-to-month, but it does help offset part of that cost. I would sell the position the first day the VIX spiked over 15.
Another variation (full disclosure, I've never put this variation on so I don't know if it would work in practice) would be to sell that 15 delta VXX put and use that to finance the purchase of a VXX call spread in a close to cash-less transaction. I forget what the skew was, but my best guess is that with VIX at 12, you'd be selling an 11 put to finance to purchase of a 14-15 call spread.
It is a profitable trading strategy in the long run if you reduce your cost basis and offset the drag cost. I'm not sure if it is profitable if you don't offset the drag cost. The only downside is having it not work for 5-6 months and giving up while you still have a loss.