Reuters / Brendan McDermidMaking bets on volatility has never been more popular. Nor has it been riskier. For signs that investors are hungry to wager on future price swings, look no further than the cottage industry that's popped up around the CBOE Volatility Index, or VIX. Their preferred vehicles are a series of exchange-traded products linked to the so-called "fear gauge" that have shares outstanding at or near record highs. Traders have also grown increasingly fond of betting against volatility, once again using VIX-linked instruments.