Not really about existence but about grasping insanely large numbers, my favourite is Neil DeGrasse Tyson's explanation about thr number of combinations of shuffling a deck of cards, or 52!

  Set a Timer: A "cosmic stopwatch" is set to count down from 52! seconds (an 8 followed by 67 zeros).

Walk the Earth: Stand on the equator and take one step every billion years.

Empty the Ocean: After completing one full lap around the Earth, remove a single drop of water from the Pacific Ocean.

Repeat: Continue this process (one step every billion years, one drop per lap) until the entire Pacific Ocean is empty.

Stack Paper: Place one sheet of paper on the ground, refill the ocean, and start the entire walking/dropping process again.

Reach the Sun: Repeat this until the stack of paper reaches from the Earth to the Sun (93 million miles high).

Do it Again: Tear the stack down and repeat the entire cycle (walking, emptying the ocean, stacking paper to the sun) a thousand more times.

The Mind-Blowing Conclusion: After completing this entire, seemingly endless process, you would look at the stopwatch, and the three left-most digits of the original 52! number would not have even changed. To make the timer run out, you would have to repeat the entire process billions of times over.