I feel sorry that he has lost himself along the way, but his loneliness was well deserved, and honestly i dont think it was hurting him at all.....
Obito isnt who he used to be, hes changed. He's pretty much a body without emotions, he just want to obliterate people and proceed to the next world.
Part of me feels bad for him, as i have strong faith that he will find himself sooner or later and will regret the path he chose and will likely die fighting Madara just like corrupted Anakin fought back the very person who changed him in the first place.
If Obito finds his own self again, then i shall feel bad as he will suffer from realising that he failed miserably, but when it comes to him now.... He has never seemed to be unhappy about his life, his sole suffering comes from Rin's death and that is it. If Obito was ready to kill his sensei when you could truly feel that he loved him back then its clear that Obito has lost all feelings he ever had, he is a puppet and nothing more right now.
Itachi, Sasuke, Naruto, Gaara and so on all suffered more than he did, especially Itachi, he is the most tortured soul i have ever seen in a manga and the fact that he kept his composure through it all only makes him shine even more, specially since he was still a mere kid when it started it all.
Obito doesnt suffer right now because he is disconnected from reality, if he ever wakes up then his suffering shall begin, but only then.
All i can say is that since i strongly believe Obito will die good, i cant truly hate Obito despite all that hes done, when i look at him, i can still see the kid who ready to risk his life for others, i can still see the kid who had a driven spirit like we had never seen before, and id like to think that we will see that same kid surface once more sooner or later.
The only one i hate is Madara, he is pure evil, nothing more, nothing less