I think people are turning their alts into bitcoin in the hope of ETF approval and bitcoin will rise and buy back their alts in much less satoshi than now.
That's pretty dead at the moment. I'm not sure where the optimism comes from.
If people have been dumping their alts (enough for this sea of red anyway) for Bitcoin, Bitcoin price should be surging. Instead, the $6000 support was broken for the first time in I don't even know how long. From those tidbits, one can probably conclude that money is leaving the market that and every coin is doing horribly, with Bitcoin much less so than alts.
Though bitcoin is losing value against dollar, in alts case, bitcon's value has increased a lot against alts. It is proved with decreasing satoshi value of alts and also increasing BTC dominance. That why alts are getting double hit. They are losing satoshi value in top of decreasing bitcoin price. Alts are sacrificing themselves. So, I think this has nothing to do with bitcoin's dollar price. When people will sell their dollar for bitcoin then bitcoin's dollar's price will increase, and catalyst for this is much hyped ETF approval. People thinks enough new money will enter the market after ETF approval.