Brewology

The list of mining pools is extensive - there are already more than one and a half thousand of them in the world. The vast majority of users work through bitcoin pools. The level of difficulty of mining this cryptocurrency is so high that even with a super-powerful computer, you cannot make a profit alone. Therefore, all new pools are formed. There are other cryptocurrencies, younger than bitcoin, that are faster and easier to mine. But they have no real value in the network, and you can earn them only with the hope that in the future their rate will rise, and this is more like speculative mining.

Before the advent of asic, coins were mined using video cards and computer processors. Such methods were profitable (processors to a lesser extent), however, due to the increase in power and high electricity bills, they became unprofitable.

If you look at it, then an ASIC is just a microcircuit that performs a certain type of work. And already in the 21st century, these chips allow you to decrypt the algorithms that are the basis of a particular blockchain.
It is important to note that each cryptocurrency works on the basis of a certain algorithm. These algorithms may or may not be the same for different cryptocurrencies. It is very important to choose an ASIC that is suitable for the algorithm of the particular cryptocurrency that you are going to mine.

The main principle of cryptocurrencies and blockchain implies that the more people own this or that coin, the more decentralized it is. And the more this decentralization, the more stable and efficient the whole system.
https://miningasic.com/
In order to prevent the centralization and disappearance of cryptocurrencies, many blockchains create hashing algorithms that are resistant to the use of ASIC hardware.