In Trump's original post, he is "calling for" the rate cap, which I interpret differently to "mandating" a rate cap. The Guardian article seems to think that the executive has no authority to compel banks to comply, and this might well be the reason he is merely "calling for" this rate cap.

And if this is the correct interpretation, then this was communicated in a very confusing way.

Seriously read Basic Economics

Not enough % return on risk and the company cancels their service and consumers have to go to loan sharks or get even more desperate and ready to do whatever they need to to survive

Wow, this is great! It's frankly wonderful we have a president we trust with these decisions. Can you imagine the congressional hearings that a move like this from any of the other presidents we've had since 1988? Media would have freaked out, markets tumbled. There would have been impeachment rumors. But now? We get "just the facts" reporting, and it just happens. No hearings, no media frenzy, market soars.