Have you read the whitepaper? https://bitcoin.org/bitcoin.pdf

It discusses how centralized payment processors are fundamentally flawed because they provide a centralized entity to dispute transactions with. A "bank" cannot even issue such a currency due existing regulation; the SEC would likely view such a currency as an unlicensed security offering. Look into IPO regulation if you're interested. It's an expensive thing.

Furthermore Bitcoin's finite eventuality is not centralization. Miners are profit seekers. Mining profits are a function of exchange rates and market share. The difficulty for solving a block has been growing exponentially and unsustainably. A small operation can enter and exit the mining pool more easily than larger operations which require long contracts and massive overhead. Therefore, as Bitcoin's price fluctuates, we should witness a dynamic mining pool where smaller operations who pool together have an advantage over larger operations.

Additionally these new ASIC chips will only become cheaper as economies of scale comes into effect, and manufacturers cannot increase processing power indefinitely. Therefore we should see the mining pool consist majorly of the price efficient, older chips in the near future as the marginal return on more advanced chips continues to decrease for the market's purposes.

The growth in mining we are witnessing now is not indicative of how the market will act in the long run.