Robo advisors are becoming commonplace thanks to their considerably cheaper offerings than those provided by human wealth managers. The transparent fee and no-conflict-of-interest structure is appealing to a new generation of investors (over 60% of robo advisor clients are under 35). As a result, robo advisors are doubling their AUM every few months, but the $20b currently under management is still tiny compared to the $17t managed by human advisors.