Hello, I have a quick question regarding mining rewards.

I've been looking to invest in a few ASIC's but something is causing me a little bit of confusion. I've been looking at a bunch of calculators but with my understanding of how mining works, I'm not sure how these can be considered accurate at all.

Ignoring things like difficulty, block reward, BTC price etc, my biggest question is how can it give you an X amount of bitcoin mined per hour figure. If the rewards are only given to the miner that actually solves the hash, surely it's just completely random who gets the reward.

I.E You could wrong for 5 years and never receive a single bitcoin for your troubles. Is this just a pure probability answer? Do these calculators assume that you are mining in a pool of some sort that gives you X amount of a block reward for each block?

Sorry if that is not a coherent question, I'm just struggling to understand how they can give you an X amount figure for your BTC gained.


Thanks!