Bitcoin climbs nearly 4% to $81,000 as ETF inflows, strategy buying support rally

Bitcoin climbed above $81,000, supported by U.S. spot ETF inflows and renewed buying by Strategy, while Ethereum and major altcoins also advanced. Experts remained broadly bullish but flagged stretched momentum, with Bitcoin’s daily and hourly RSI in overbought territory and key resistance around $81,000-$81,500 and $83,300.