If isolation just means being a NEET, then yes, I believe it is possible. It depends on the person. I have spent long periods of my life being a NEET and in isolation. Due to personal circumstances I am forced to move around the world a lot, so never kept down a job or had a home, no family or friend around. While the technical difficulties of such a lifestyle (paperworks, taxes, visas, lack of citizenship rights, no one to teach me how to adult in the first place, real estates, moving etc) wear me down horribly, the isolation is one of the pros for me. I would not have it any other way. I enjoy my own company very much, I think it is just in my nature to thrive in isolation. Just keeping contact with family overwhelms me already, I truly do not desire more.
If you still have to wonder, though, perhaps you are not cut out for it. Many people are depressed because they feel inadequate with themselves.
In my early 20's there was a time when my laptop broke and I did not have a smartphone or TV, not even a music player. I was out of work and spent some months just reading and listening to the rain (it was monsoon season). It was beautiful. Never even contacted my best friend. Living condition was pretty drab but I felt so, so happy. I knew then that I truly love being alone.