1) Don't solicit publicly (i.e. don't make a business out of convincing non-affiliated retail investors to invest in Bitcoin; you can still band along with friends, family, and fools in a non-scalable fashion)
2) Do solicit publicly, but go through the disclosures-and-compliance process that society has decided should gate scalable access to retail investors' life savings
The cryptocurrency economy is largely unwilling to do #2, which is onerous, expensive, and (ahem) exceedingly difficult to get through if you have produced nothing of economic substance.
Not that I think it would be a great idea for anyone to sink their life savings into Bitcoin right now, but I think the SEC could do their job protecting investors without literally creating a 2-class system of rich privileged people and restricted poor people. For example, they could set limits on the percentage of your income or net worth you could invest in risky opportunities. That would allow people of all income levels to participate.
Bitcoin futures are legal. The principal issue ETF sponsors are running into is constructing an index. The SEC isn't thrilled with indices referencing trades on e.g. Bitfinex.
If we must do this can we just make a rule that all ultra-rich people and only ultra-rich people automatically get 20% more riches a month, or week, or day, and NOT burn the impossibly huge amounts of energy that expanding cryptocurrency will incur? I am not at all sure it's possible to stop capital concentrating this way, but I do think it is peculiarly horrible to have it doing so by a mechanism that intentionally and pointlessly burns energy in an ever-increasing fashion, when we're already in serious trouble through our collective eagerness to burn energy.