Replying to Good Camera/lens/computer combos.

I'm currently shooting RAW on a Nikon D3300, with the stock 18-55mm lens and an older 70-300 lens. My pictures on hill look great, and even when I get home, they still look sharp (sometimes the cold and the elements does tricks on my eyes, so when they look good on the mountain, they end up not looking too good inside). My problem is the transfer process from camera to Instagram/VSCO/other media outlet. When I would be in a bind and have to use a friends SD card reader for my phone, there is minimal noise and looks great. When I use my computer, somewhere through the upload and email process, they get grainy and noisy. Am I an untalented reject who needs to find a new hobby, or is this a common issue?