I’ve been going down a rabbit hole lately regarding Bitcoin’s long-term security budget, and it feels like it doesn’t get nearly as much attention as price action, ETFs, and institutional adoption, what happens when the block rewards eventually grind down to zero?
Whenever you bring this up, the standard response is always, "Don't worry, the fee market will take over and miners will stay incentivized."
But does that actually hold up?
Don't get me wrong, I get the counterargument: as Bitcoin grows, block space becomes incredibly scarce, and future settlement demand could make transactions valuable enough to sustain miners. But the reality is that the block subsidy keeps cutting in half every four years. Right now, transaction fees are still just a tiny drop in the bucket for miner revenue during normal periods. Most of their income still comes from that shrinking subsidy.
One thing that keeps bothering me is that every security-budget discussion eventually comes down to assumptions about future demand. We’re being asked to predict what users will be willing to pay for block space decades from now, and that feels like a much harder problem than many people admit.
To make things weirder, the ecosystem is aggressively pushing to move activity off-chain to Layer 2s and sidechains. It feels like a total paradox. For Bitcoin to scale globally, it
needs L2s. But if L2s do their job too well and compress millions of transactions into just a few on-chain settlements, they might accidentally they might accidentally reduce fee pressure on the base layer pressure on the base. If there's no fee pressure, the security budget takes a massive hit.
Now, researchers like Pierre Rochard argue these fears are overblown. His point is that Bitcoin’s security isn't a fixed budget—it's a dynamic market. Between transaction fees, mining competition, and the difficulty adjustment, the network has built-in ways to adapt and stay resilient.
https://www.thestreet.com/crypto/markets/analyst-calls-bitcoins-security-budget-argument-a-category-errorBut here’s what I can’t seem to reconcile: both sides agree the subsidy is disappearing. The disagreement is whether future demand for block space will naturally fill that gap.
Maybe it does. Maybe Bitcoin becomes such a valuable settlement network that users willingly pay for scarce block space. But that still feels more like a prediction than a guarantee.
Even if hash rate drops in the future, the difficulty adjustment keeps the network running. The real question is whether the cost of attacking the network remains sufficiently high relative to the value being secured.
Am I missing something obvious here, or is the security budget one of the biggest unanswered questions in Bitcoin’s long-term future?