I wrestled with this numerous times in my head. Looking at it from every angle to see where the pitfalls are. At this time, I cannot see any.
The only thing I came up with, which will not happen soon since it is not in place, is Wall Street shorting. I know the futures market is open but they dont have the naked shorting that enables big time manipulation. Could that be coming at some point? I am sure it will. With the market so small, relatively speaking, this would allow the shorts to blast many tokens to oblivion with little money.
Of course, as the total market cap increases with the money invested from others on the Street, this makes it less likely the further along with go. However, we are still a rather minor industry for the vultures...hell they manipulated the gold market and that is 10 times the size of this one....so a lot of growth is needed before the shorters enter the picture
Outside of that, blockchain technology is growing at such a rapid pace that I am not sure even Wall Street can "bubble" it. They could push the market cap up ten fold yet the technological advancements of blockchain will go up 1000 fold in the next year. There are millions of developers hacking away at code creating all kinds of things...we are at the beginning of the innovation age...something like we havent seen before.