[gamblor956]

In the case of unsanitary food preparation, it very well could be a killer idea.

By the way, none of those other ideas are illegal (in the US). Taxi drivers can own their own cabs; some do but most do not due to the expense of acquiring/maintaining an adequate vehicle. It's always been okay to rent your "spare bedroom" to strangers--just as long as you occupy the remainder of the unit (though whether your lease or HOA agreement allows this is a separate issue). Sharing your physical copy of an artistic work has always been allowed. Private mesh networks have never been illegal. Cryptocurrencies are legal forms of exchange (or in this context, "consideration") between two consenting private parties, just like any other form of property.