Mining rewards are given to those miners who resolve the puzzle first. The probability that a participant will find the solution is equal or greater than the share of the total network mining power.
Participants who have a low percentage of mining power have a very slim chance of finding the next block by themselves. A mining card one could buy for just a few thousand dollars would be less than 0.001%. The chances of finding the next block are very low, so it can take a while before a miner finds one.
And the difficulty going up only makes matters worse. The miner might never be able to recoup their investment. Mining pools are the solution to this problem.
The third party operated the Mining pools and coordinated groups of miners. Miners can receive a steady stream of bitcoin by working together and sharing the payouts between all participants. You can see in detail the mining pool statics on Blockchain.info.
I Forget Mining. Any Other Way to make money from cryptocurrency?
The easiest way to make money from cryptocurrency is to buy bitcoin on one of the numerous exchanges. Alternately you could also use the “pickaxe strategy.” This strategy is based upon the old wisdom that the smartest investment during the California gold rush of 1849 was not to mine for gold but to make pickaxes for mining.
You can invest in pickaxe-making companies to modernize the situation. A company that makes equipment for Bitcoin mining would be the pickaxe equivalent. For example, you might look into companies that manufacture ASICs or GPUs.