Based on my knowledge bitcoin mining is where you get bitcoin for free from a hash or the power of the machine power you get sometimes you get more depends on the hash power you had and as of now bitcoin mining ia not profitable right now fhere are plenty miner there that uses high powered bitcoin miner and we cant conaider our self as one.
We cannot consider the bitcoins generated from mining as free because we have to invest a lot of money on hardwares and all those things we buy for mining, and mining is that when the machine with the maximum hash power keeps running until it finds a block which gives it a reward for that and like that you get bitcoins for you investment, that is what i know about it, and the more hashpower you machine has the higher chances would be of finding a block.