"Real banks" are highly regulated and in the US are backed up by the US government. I don't know of too many other entities that can handle other people's asset

"Real banks" are highly regulated and in the US are backed up by the US government. I don't know of too many other entities that can handle other people's assets with such low reserve requirements without being considered fraudulent. If there are any, I suspect they're heavily regulated or at least exempted as a speculative private fund.