So they can accumulate from three main sources now.
1. Miners. Whatever the miners are selling is getting snapped up every day.
2. OGs. There are thousands of bitcoiners who are at a point now who feel they can live off their bitcoin, while being able to survive even the unlikely ~80% winter. There will be more of these people each cycle (or period of time). And even the ones who were set in one of the last "cycles" may still be selling. Even if they are selling just small amounts to maintain a baseline lifestyle I would imagine there are enough to provide quite a bit of the reason why we are flat for 2025.
3. The people who either do not understand bitcoin or are just weak. People who see it as an investment. Maybe got into an ETF and now want to lock in the "gains" before the crypto bear they hear about constantly.
Best way to shake as many coins loose from each?
1.Miners: Natural sellers with big capex/opex and razor thin margins (always selling)
2.OGs: Create confusion by violating all established tradable patterns. Convince em wild wild gains are over but winters might not be- and that this is a good, historically high price to sell at for "diversification", bear "hedging" and the finer things in life. (currently happening)
3.Noobs: Scare/greed em out on 10-20% moves in either direction. "CUT YOUR LOOSE" (currently happening)
My guess is number 2 more than anything else.
If you got in early but not a crazy amount of coins say 50 coins or less
Selling 2 gives you 220k which could allow a long hodl
But many in that spot may be selling 10 coins which could allow for 7 to 8 years of living.
Agree... I think assuming that someone with double digit BTC holdings could be either selling as you suggest or even doing the DCA sort of withdrawals. Older holders might not need as much behind while the younger ones might want to start this with a bigger stack. At a 0.5-1.5 BTC/year burn rate even a family can be supported. And if the person keeps outside income then the number can be less.
I imagine a LOT of people in BTC for 10+ years are using their value for things other than savings now.
In which case the buy pressure is NATURALLY biased more to the sell at retail than it has been in the past. While the buying pressure is in the dark pools of OTC.
Finally... here is a chart of the balances held in exchanges... It has been dropping for more than a year and is accelerating seemingly.

I agree with you, it is a completely logical observation, long-term holders are now gradually using their accumulated BTC to meet living expenses, or to invest in new opportunities, this is creating natural supply pressure in the market, but it is not a panic sale like before, but rather an indication of stable usage.
At the same time, the continuous decline in exchange balances shows that real holders are now also, Self Custody, which is a bullish signal in the long term.
The retail buying avalanche or, Retail bias, is increasing especially because new investors have made small amounts of DCA, while the old ones have gradually withdrawn, it is actually a kind of generational change, those who saved before are now using, and those who are new are starting to collect!