The ultimate question is: How far do you need to go until you believe that the earth is indeed not flat? Do you trust your teachers? Stand on a tall building? Take a balloon ride? A plane? A spaceship? Then still, at which point can you rule out that the earth just appears to be a ball due to some yet-to-be-explained phenomenon (gravitational anomaly?) but is indeed flat? (The correct answer of course is "turtles all the way down").
For some definition of 'easy', yes. You still need to know a lot about how a CPU works. I think a project to bootstrap a PC with code generated from a completely verifiable platform would be really cool, but in practise would be of limited usefulness above and beyond secure boot we already have, because you're still trusting all the binary BLOBs you can't control (BIOS/UEFI, Intel ME, microcode, etc)
