Quantitative Easing (QE) has basically become the primary role of the FED in the last decade. It involves injecting liquidity (printing money) into markets. Very inflationary if not balanced with high interest rates.
The BTC-people have a counter-theory of Quantitative Hardening whereby the inflation caused by QE makes anti-inflationary assets like BTC look more appealing, as people put more of their wealth in BTC, the free supply of USD becomes even more abundant causing more inflation. A virtuous cycle that ends with hyperinflation of fiat and hyperbitcoinization (mass adoption).
People say that BTC doesn’t scale but today BTC Base Layer handles about the same number of daily transactions as the ACH system. Second layer (L2) solutions like Lightning are sort of taking the role of credit cards by providing cheap instant payments, while L1 is becoming the value settlement layer like ACH.
Its neat cause anyone can be a Lightning Service Provider (LSP) and offer liquidity on lightning at whatever fee they want. Basically anyone can become a credit issuer for BTC, opening a free market for service with fees an order of magnitude lower than credit card companies. The only cost to become an LSP is the opportunity cost of locking up BTC in payment channels for others to use. You still own the BTC and you earn transaction fees from it, sort of like earning interest in a savings account.
It’s quite possible that we still use USD in a Bitcoin world. Only the USD is pegged 1:1 to some amount of BTC. This would mean the end of fractional reserve banking and a new emphasis on transparency in financial institutions. Unlikely that the legacy banking system would adapt to such a system. They might see the same fate as Blockbuster, while the Netflix of Banking becomes a new industry.