If there is one subject that seems to divide the large financial investors and investment banks, it is Bitcoin! While the stunning year the cryptocurrency has seen to date has amazed all with its 700% growth, some have not always been too complimentary about it. One exception to that had been Morgan Stanley CEO James Gorman who, while not gushing in praise, had not been overly critical of it. In recent comments though, it seems he may now be taking a more cautious stance on Bitcoin.Although his recent reported comments were not scathing as such, he did take time to point out a few concerns he had around the cryptocurrency. The first was that he didn't think the attention Bitcoin was currently getting was deserved or healthy. It seems he fears that the widespread popularity of the cryptocurrency may be leading to a speculative bubble to build up. In his opinion, the fact that the popular cryptocurrency has shot up by so much in a relatively short space of time is proof in itself of the speculative nature of the Bitcoin market.On the face of it, the main worry about an overheated and speculative Bitcoin market lies in what might happen if the bubble were to burst. If the market price were to take a sudden dive down, it could obviously spell financial disaster for a lot of investors (many normal members of the public) who had jumped on the bandwagon. This kind of financial crisis is not what Wall Street, or indeed the world, needs after the last one.Of course, many Bitcoin advocates who have experienced great success by buying into the cryptocurrency early believe these sentiments from Gorman to be sour grapes. In some quarters, it is thought that the major banks like Morgan Stanley are simply upset at missing the boat on Bitcoin and the huge returns it has seen. It is also thought by some that they do not like the way that Bitcoin opens up their world and the riches it can bring to normal members of the public to profit from.