Yep its in the title. It's a hobby. So in full its called an electronics hobbyist
There are lots of other hobbies that people have. Some like to build RC planes, some like to make wooden furniture, some like gardening, some do knitting, some collect stamps, some people modify cars, some people shoot pieces of paper with a gun, some like to go fishing. Explain it to them using those examples. People don't go fishing because they are hungry and need food, or plan to haul back one full truckload of fish to sell to food processing companies and make a profit. So why are they doing it? They don't really get anything useful out of it! Well.. They enjoy the piece and quiet of floating along a lake in a small boat and seeing what they can catch out of that lake. I personally don't see how that would appeal to me and it all sounds pretty boring, but i can see how some people do enjoy it and i fully respect that.
I personally believe that every person should find at least one hobby. It gives you something to live for, something to help you relax after a hard day or hard week.
If anything electronics is actually one of the more productive hobbies since it can lead to a decent career in the field. Pretty much all of the good electronics engineers started off as electronics hobbyists. Its a very board and complex field that takes a lot of knowledge, so only people who are truly passionate about the subject actually have the dedication to learn so much of it.
EDIT:
Oh and people in this field tend to also be very technical minds with a good understanding of science. So they can do well in pretty much any engineering field. They like to know why and how things work. So someone who is an electronics engineer can likely look under the hood of a car and point out what the stuff under there is and what it does, even if they are not into cars and never worked on one, while an average joe that is not into cars will call anything under the hood as being 'the engine'.