Not true:

https://en.wikipedia.org/wiki/Turbo_(finance)

There are, as said, depending on juristic regime, products which do not let you lose more than you invested.

On top of this comes national regulation: E.g. in some EU countries, retail traders are exempt from s.c. "margin calls" and the broker is required by regulation to "just close and not ask for more"

Source: Im living in one of these EU countries