A couple of ways to read this, imo.
could be genuine conviction, people who bought years ago just don't care about a 50% pullback and aren't selling regardless of price action.
could also just mean supply is getting more illiquid over time as more coins get held by long-term whales and institutions, which isn't really a bullish signal on its own, just a structural shift in how much BTC is actually available to trade
Bitcoin is different now compared to its early years. Even after a big drop, people are not panicking the same way anymore, especially since institutional investors are still holding.
Many are probably looking at the current price as a good chance to slowly buy and prepare for the next halving. Based on the previous cycles, Bitcoin usually becomes stronger around that period.
So instead of leaving the market, some are already building their position early and waiting for another possible all-time high.
This is because investors has learnt to trust Bitcoin over time, due to it historical and tract records of tracing back in price even when it gets to a all time low. The time people used to Panic and sell when even there was the slightest change in terms of the market price was those early days, when bitcoin was still trying to break through.
These days investors has learnt to trust Bitcoin because, over time they have come to the realization of the facts that Bitcoin is not what been afraid based on experience which they have gathered over the years. At this point in time anyone who is afraid of investing in Bitcoin should be considered as a newbie because, only people who are new to Bitcoin will be afraid of investing in it.
Bitcoin has proven time without number that it can give investors profits by bouncing back and hitting all time record. So when you see people hold back their Bitcoin holding over time no matter the low that Bitcoin records just know that they are matured enough to handle the pressure which comes with change in price.