Here is what concerns me. I am a gold and silver bug. So I buy and keep as much gold and silver as I can afford (yeah Bitcoin too).
But I fully understand that the price of silver and gold is heavily controlled and kept down. While I only invest in physical bullion, most people don't bother to buy physical billions.  They just buy gold and silver certificates which their bank tells them represents an actual gold bar they will kindly store for you.

So you can actually go to your bank or broker and buy a gold certificate. It will have a serial number which they tell you is matching an actual gold bar somewhere in their vault.

What they are not telling you is that this same certificate can be issued to several other customers. So they effectively sell the same bar to many people. This scam can only work so long as not everyone decides to cash in their certificate and demand their physical gold. And in fact the vast majority of paper gold investors never bother to cash trade in their certificates for actual gold or silver.

The problem with this is that gold and silver are valuable because they are scarce. But when they issue several 'certificates' for the same bar, they are effectively creating the illusion that there are more bars in circulation than there actually is. And the more paper gold they issue, the more they create the illusion that there are more gold in circulation. And this has for effect to keep the price of gold down.

My fear is that if Wall Street actually gets around to invest in Bitcoin, they will not issue any actual Bitcoin to their customers anymore than they are issuing actual gold bars to their customers. They will just sell 'paper Bitcoin' or bitcoin certificates to their customers. 

Some people call this rehypotecation, some others call it fractional reserve banking. But I call it what it actually is - fraud and price control.

What are your fears that they might actually implement these things if Wall Street decides to sink their teeth into Bitcoin?