George Gammon made another video 21h ago, in which he explains it in depth[1]. Then again, i don't understand that situation with the financial instruments, and indeed it may not have been wise of me to mention it.
In the broad economy however, any protectionist regulation, any anti-monopolist regulation, any protection from myself like narcotic laws, and a myriad of other things, creates bubbles.
In the economy, following Adam Smith's invisible hand, any decision not taken by the individual, but is imposed upon him, and this decision carries along with him a financial cost, creates bubbles. It is that simple.
When an individual wants to hire an Uber instead of a cab driver, there are certain factors influencing his decision, like cost, convenience, quality of service and more. When an individual wants to hire an Uber but he can't, then the inferior product or service will continue to be profitable, until the individual finds a way to get around the laws and regulations.
When that happens, then the people who offer the inferior product or service, lose their source of income in a moment's notice. That's when the bubble pops.
The bad situation here, is that a lot of people will lose their source of income all at once, instead of it being gradual. That's why creating bubbles is not advisable, and it creates explosive and dangerous situations.
In Uber's case in Greece, they are banned somewhat, because as a company they have revenue from Greece, but they don't pay taxes here.
[1] https://www.youtube.com/watch?v=0S3NLXBjJdQ