What would the world be like if Bitcoin still exists and is widely used 100 years from now?

This is a profoundly grand and imagination-capturing question. If Bitcoin not only exists but is widely used 100 years from now, it would signify its successful evolution from a niche speculative asset into the foundational infrastructure of the global socio-economic system. Such a world would be fundamentally different from the one we know today.

The contours of this world can be sketched across several dimensions:

1. Reshaping the Global Financial System: A New "Digital Gold Standard"

Bitcoin as the Ultimate Reserve Asset: Like gold in the past, Bitcoin would become the ultimate store of value for global central banks, large corporations, and funds. Sovereign currencies (USD, EUR, CNY, etc.) would still exist for daily transactions and taxation, but their value would ultimately be pegged to Bitcoin, or at least backed by Bitcoin as the primary credit anchor.
The "Physical Law" of Money: Bitcoin's hard cap of 21 million coins would become the immutable "fundamental axiom of value" in the global economic system. Governments could no longer dilute wealth, transfer debt, or fund wars through unlimited money printing. This would force nations to adopt more responsible fiscal policies, living within their means.
Evolution of the Banking System: Traditional banks would see some functions diminished (like money creation), but they would evolve into new roles:
- Bitcoin Custody & Security Providers: Offering top-tier security services for individuals and institutions unwilling to manage their own private keys.
- Layer 2 Network Service Providers: Acting as large nodes on solutions like the Lightning Network, providing liquidity and processing massive volumes of micro-payments.
- Financial Product Innovators: Developing complex financial derivatives, loans, and insurance products based on the underlying Bitcoin asset.
Demise of the SWIFT System: Cross-border settlements would no longer rely on slow, expensive, and geopolitically influenced centralized systems. Large international transfers would occur directly on the Bitcoin main chain, confirmed within minutes at minimal cost, free from censorship or blocking.

2. Shifts in Economics and Individual Behavior: From "Consumerism" to "Saverism"

Prevalence of Low Time Preference: Under a deflationary (or stable) monetary system, the purchasing power of money would increase or remain stable over time. This would fundamentally alter behavioral patterns. People would become more inclined towards saving and long-term investment rather than immediate consumption and debt accumulation.
Deepened Understanding of "Proof of Work": Societal culture would place greater respect on behaviors that create value through real work. Since the money itself is created by consuming vast energy (Proof of Work), this "honest money" imprint would permeate societal values. People would hold greater disdain for unearned gains achieved through financial games and monetary inflation.
End of Debt Culture: The current fiat-dominated world is essentially a debt-fueled world encouraging borrowing. In a Bitcoin-based world, due to money's scarcity, borrowing costs would be higher, leading to greater caution. Society would shift from "borrow-to-consume" to "save-to-invest."

3. Transformation of Nations, Sovereignty, and Geopolitics

Re-balancing of State Power: The power of nation-states would be significantly constrained. The inability to print money to cover fiscal deficits would likely lead to smaller government sizes and a corresponding reduction in their ability to intervene in the economy.
Shift in Geopolitical Power: National strength would no longer depend solely on military might or control over the world's reserve currency (like today's USD hegemony). Energy resources (for mining), technological innovation capabilities, and Bitcoin reserves would become crucial new dimensions for measuring national power.
True Empowerment of Individuals: Anyone with an internet connection could access this global, permissionless financial network. This would represent the largest financial enfranchisement in human history. People living in countries with hyperinflation or unstable financial systems would possess a reliable store of value to protect the fruits of their labor.

4. New Paradigms in Technology and Innovation

Mature Layered Architecture: The Bitcoin main chain (Layer 1) would function like a national highway system, dedicated to high-value, low-frequency final settlements. The vast majority of daily micro-payments would occur on Layer 2/3 networks like the Lightning Network, enabling instant, near-free transactions.
Symbiosis of Energy and Computation: Bitcoin mining would become the ultimate balancer and consumer in the global energy market. It would utilize otherwise wasted energy (e.g., stranded gas, excess solar/hydro), driving renewable energy development and optimizing energy grid efficiency.
Realization of the Internet of Value: If today's internet enables the free flow of information, the Bitcoin-based future network would enable the free flow of value. Machines could automatically conduct micro-payments between themselves, spawning entirely new business models (e.g., your self-driving car autonomously paying tolls and charging fees).

Potential Challenges and Dark Sides

Of course, this future is not a flawless utopia:

Vast Wealth Disparity: Early adopters and Bitcoin whales would amass staggering wealth, potentially creating a new "digital aristocracy." How society addresses this unprecedented wealth concentration will be a major challenge.
Privacy Concerns: The Bitcoin main chain is transparent. While addresses are pseudonymous, privacy will remain an ongoing battleground as analytical techniques advance. Reliance on privacy technologies like coin mixing and zero-knowledge proofs will be high.
The Temptation of Centralization: Even if the protocol is decentralized, exchanges, custodians, and service providers could still become "too big to fail," introducing new systemic risks and points of censorship. The ideal of decentralization will constantly contend with the efficiency and scale demands of the business world.
Transition Pains: The shift from today's credit-driven, inflationary world to a hard-asset-backed, deflationary one would be extremely painful and turbulent, potentially triggering prolonged economic depressions and social conflicts.

In summary, a world where Bitcoin is widely used would be defined by the core change of a unified, neutral, immutable measure of value for the globe. This is not merely a technological shift, but a profound social experiment that will reshape our concepts of money, power, trust, and time. The world would become more transparent and fair, but also potentially more fragmented and challenging. It would undoubtedly represent a fundamental leap in human civilization.