If we follow the concept of the tragic hero as it was proposed by Aristotle in Poetics, then the character of Tom Wingfield must reunite qualities that include a change in his fate. In Poetics, Aristotle defines the tragic hero within the parameters of he/she being someone
who is not eminently good and just, yet whose misfortune is brought about not by vice or depravity, but by some error or frailty
Under this perspective, Tom Wingfield would certainly fit the definition of the tragic hero. This is because Tom's inherent sense of duty and responsibility towards his family are the forces that obligate him to remain in a place where he is neither productive, nor happy. As a result, he becomes a victim of his role as the remaining male in a household of females who are incapable of catching up with a changing, modern, world.
However, this forced-imprisonment in a place where he does not belong begins to affect him in a way that also renders him detrimental to everyone: he drinks, he is careless about his choices, and he becomes discouraged with life, as a whole. Hence, his circumstances leave him unable to make really good choices for himself.
Additionally, Tom lives in a time and place in history and society where he is really not too free to make the radical moves that he would need to make to liberate himself from the stagnant atmosphere of his home, led primarily by his mother and sister. The financial oppression and mental suffocation that he feels begin to eat him up inside. In the end, he finds no other choice but to follow his instincts, and simply leaves without looking back.
We know that he never mentally leaves his sister, Laura. He begs in the end to fate to help him help her, somehow, "blow out her candle". This refers to his wish to see her catching up with the world, as well as his desire of forgetting her memory, for good.
Conclusively, Tom never changes from bad to good. In his very own words, we find out that his only success was having left the home; and nothing else
I didn't go to the moon, I went much further - for time is the longest distance between places. Not long after that I was fired for writing a poem on the lid of a shoebox.[...]I pass the lighted window of a shop where perfume is sold. The window is filled with pieces of coloured glass, tiny transparent bottles in delicate colours, like bits of a shattered rainbow.Then all at once my sister touches my shoulder. I turn around and look into her eyes ...
Oh, Laura, Laura, I tried to leave you behind me, but I am more faithful than I intended to be !
Therefore, Tom's fate is nowhere more cheerful, simply more liberating. Yet, he is still imprisoned, only this time it is by the memory of Laura. He seems bound to his fate, after all.