https://www.investors.com/etfs-and-funds/etfs/everyone-calls-bitcoin-investment-trust-an-etf-but-its-not-heres-what-it-is/ Look at this option , these folks have well over 150k bitcoin in their fund. Similar to an ETF but not exactly the same.

Also see my replay to Bitcoin, if it becomes a widely used currency with a store of value will be deflationary for anyone who uses it in parity with goods and services. Unlike Fiat, there is no INFLATIONARY weapon in the arsenal. There can only ever be 21 million whole bitcoins and in reality there will only ever be about half hat in circulation.
ALSO Do not over look the idea of an occasional FORK as in Bitcoin Cash or Gold which, contrary to all rhetoric has been the equivalent of a stock split without the split.