Machine learning is simply a process that eliminates the need for a person to physically program a machine to act according to a user’s preferences. The most prominent example of this is when the ads on a site like Facebook promote deals on items that you recently searched on Amazon. This is not the machine developing a mind of its own, but rather an algorithm that has made your computer “smart” enough to show you what you like without anyone having to tell it to do so.
This same algorithm is also used in all that smart home tech that automatically adjusts your thermostat based on your habits. And what we should ultimately be concerned about is the safety of all that data, rather than the possibility of tech thinking for itself. Hackers are the true threat when it comes to machine learning.