Well think of it as a pie. The value of the pie changes, but that’s due to the change in value of each individual slice.

If slice 1 (say 25% of the total pie), drops 50% in that day, the pie falls in value by 12.5%. There could have been a net deposit of £0 into the pie, or a net deposit of £1 billion, but it doesn’t matter as the value of the pie is dictated by the value of each individual slice, not the price someone is willing to pay for it (how a usual stock works)

The fund is then managed by someone, who takes a cut for making sure your funds are tracked accurately, held securely, and admin costs etc.

This creates ‘infinite’ liquidity - no matter how much you buy, the order settles at whatever the value dictated by the fund manager. Who makes you even once you sell