4K right now is for the most part.. kinda pointless. Not saying to not shoot in 4k but reality is - unless you have a computer to handle 4k - how will you benefit?
Also keep in mind that MANY users get bored with the whole "press record, fire up motors, take off, fly around in circles for 10 minutes, land, turn off motors, press record (off)" motion. So at little bit of effort on editing goes a long way!
Things to think about -
Do YOU have the ability to watch 4k? TV, Laptop, Tablet, Phone, ect.
Do YOU have a computer able to handle 4k video files/editing?
Do YOU have enough storage space to store those large 4k Video files?
Do the masses in the world have a computer able to stream 4k from youtube?
Do the masses in the world have the bandwidth to stream 4k from youtube?
Right now 4k is much like buying a ocean front property in the mountains! It'll be great once the world catches up!
I have a macbook that can handle up to 5k! 4K is handled like a champ. However most my footage is shot in 1080 for the time being. But at times I do mix it up with 2.7k
Hope that helps!