How did this trend start?

ear stretching has been around for thousands of years and stretched piercings themselves are probably almost as old as piercing itself.

Ear lobe and ear rim piercings can be found in most tribal cultures, ear lobe stretchings can be found amongst the people of Northern India, Burma, ancient Egyptian culture (the mask of Tuttenkharmun has a stretched ear lobe) and African tribes in and around what is now Kenya. Ivory ear plugs are worn by African Samburu warriors whereas the Masai and Pokot peoples wear many rings in stretched ear lobes, this was also common practice with some of the plains tribes in North America.

as for how it’ll look in 5 or 10 years ( assuming you mean remmoving the piercing ) thats going to depend on the size that the piercing has been stretched to also the method of stretching is a factor and your age but if the ear was properly stretched it can have the ability to close back up but its has been known for only slightly stretched ears not to heal back up

hope I helped you :)