BTC market capitalisation is currently at ~45%
What does this means for ALTS?
Relative to BTC altcoins will be loosing value, the market capitalisation of BTC has only increased 5%, imagine another 15%?
Please note that market capitalisation of BTC always increases in a bear market after drastic moves - it's now clear we are in a bearish trend and capitalisation has broken out (check trading view charts) so stay diligent.
As you already said, it is absolutely normal that Bitcoin itself is losing not as much as almost all other coins during a bear market. I am following the crypto market since around 2017 and so far the behavior and the movement of the crypto market has pretty much always be pretty similar during bear and bull markets. In a bear market the altcoins are suffering the most, especially the ones that are pretty new and small. My portfolio mainly consists of small and new projects so don't even ask me about my portfolio value

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During a bull market, bitcoin is usually the first coin to rise and it takes some time until the other coins are rising too. Then it is possible though that those coins are rising even more than BTC itself.