On CNBC's Squawk Box Ray Dalio, the founder of the world's largest hedge fund spoke negatively about bitcoin stating "It's not an effective storehold of wealth because it has volatility to it, unlike gold. Bitcoin is a highly speculative market. Bitcoin is a bubble."; he went on to say that it could be a currency and work conceptually but the speculation going on hurts it. Source
With the price of bitcoin increasing as of late there have been increasing amount of people coming out stating that it is a bubble; conversely there are enthusiasts who claim that people simply don't understand the cryptocurrency; the WSJ reflects on recent bitcoin news and shares the wide variety of perspectives from their readers. Source