This assumes that you will have an income of something worth more than the US dollar to pay the mortgage with. If your income continues at the same amount of US$ then your mortgage payment will still cost you the same amount of income, regardless of how the global valuation of the US$ changes.
This depends a lot on the type/source of the freeze. What were you doing at the time? Are you experiencing regular crashes? What is your hardware like? (laptop/desktop, year, make, model)
Is it just the window manager/desktop environment? Ctrl + Alt + F7 should take you to a different TTY session where you can login and give a reboot command. (actually any F# key should work)
The sysreq keys should always work if the OS is locked up. How are you using REISUB? Do you know what instruction each letter sends? Are you waiting in between pressing them? If using this “borked your PC”, the most likely reason is that your system was busy writing something to the hard drive that is related to the OS and was interrupted. How was it “borked”? Did your bootloader start? Did your OS try to start?
One thing you can do if nothing seems to be responding is tap the NumLock key. If the indicator light changes you know 3 things:
If the light changes then you should be able to tap the power button for a soft reset/graceful shutdown.
If the light does not change then you should first check your keyboard (is it plugged in? is it wireless? does it need a new battery?) but if that’s not the problem then all you can do is force a shut down, because the system is not responding to input.
There are a lot of potential problems that can produce a “freeze”, with the most basic being an issue with the mouse/keyboard or the USB port they’re plugged into. I once thought my computer was freezing because I was using a Logitech wireless mouse that was bound to 2 different USB receivers plugged into different computers, and the input would randomly switch from one to the other (seriously check the simple stuff first). You could also have a problem with your RAM, hard drive, GPU, CPU or motherboard which could each produce symptoms like freezing. If you have regular crashes you should be checking your hardware.
To really answer the question “what can I do?” requires more context, and requires you to do some checking to judge the severity of the crash.