pension funds dont day trade, they buy and hoard. so there is not much daily inflow.
many funds just buy up a basket of assets and then internally hold.. then just internally swap shares between their clients who buy in-sell out of categories of assets
....
the reason many people see financial benefit to invest in ETF instead of buy bitcoin direct is this
imagine your salary is $100k (~$72k post tax income) and you want to dedicate 7.5% of your income to buy bitcoin
7.5%=$5.4k = 0.153btc at todays price (1btc=35.4k) leaving you with $66.6k spending money
now imagine your employer put your 7.5% pretax, and employer matched that into etf shares
15%=$15k = shares pegged to 0.424btc at todays price (1btc=35.4k) leaving you with $67.4k spending money
so you have more exposure to more gains and you have a lil extra in your pocket
and you just sit on that 0.424 pegged shares until you retire, instead of 0.153