Of course the rate can change.
If you could lock in a low rate for a long period of time, most people here would be using margin loans.
You simply cannot compare a margin loan to a mortgage.
This. As intriguing as they are in certain situations, the downside risks are
serious. For Pete, having something "new" to explore and discuss has a different kind of value. Adding another talking point to his mighty arsenal is far more lucrative than the margin loan risk he took. For most, that simply isn't so.
To be clear, margin loans can be extremely useful in certain situations, but they are always dangerous to deploy without complete understanding of their exponential risks.
I'm not being critical of Pete, just pointing out that his marketing brilliance has made him very rich. Happily, his guidance has made a lot of other folks rich as well. Teaching so many people how to manage their financial lives and take better care of our finite planetary resources is a fantastic accomplishment.