Avalanche founder Emin Gün Sirer has warned that Bitcoin may face a long-term security issue as miner rewards continue to fall after each halving. Summary Emin Gün Sirer says Bitcoin’s future risk may come from falling miner rewards. Up to 20% of Bitcoin miners may be unprofitable. The debate centers on whether fees can replace shrinking Bitcoin block rewards. Sirer argued that Bitcoin’s reward model could become a larger concern than quantum computing or rival tokens. His view centers on whether miners will still earn enough to secure the network when block rewards keep shrinking. Bitcoin’s security budget faces fresh debate Bitcoin miners secure the network by using computing power to validate blocks. They earn block rewards and transaction fees for that work. The problem is that block rewards fall by half during each Bitcoin halving. Over time, transaction fees may need to carry more of the cost of keeping miners online. Crypto.news recently reported that CoinShares estimated 15% to 20% of the global Bitcoin mining fleet may be unprofitable under current conditions. Older machines and miners with high power costs face the most pressure. The same report said Q4 2025 was the hardest quarter for Bitcoin miners since the April 2024 halving. CoinShares also said hashprice fell near five-year lows, while listed miners’ average cash cost to produce one Bitcoin reached about $79,995. Sirer points to a possible technical path Sirer suggested Bitcoin could use a pre-consensus layer to reduce the load on the base network. He argued that such a design could help Bitcoin process activity more efficiently. That idea may face resistance from Bitcoin users who prefer limited changes to the base protocol. Bitcoin’s community has often moved slowly on large technical changes, especially those seen as changing its security model. Sirer’s warning that shrinking rewards pose a bigger risk than quantum computing remains a debated claim. It depends on future Bitcoin fees, miner costs, hardware gains, and market price. CZ’s recent comment was also taken out of context by some accounts. He said Bitcoin could only be replaced in theory by better technology, while still calling BTC “global money.”
