In life, we all have choices, and choices all have consequences. When we make a choice, we must, by definition, accept the consequences of that choice.
If a person chooses to break into another person's home, with the intention of stealing that person's property or doing them harm, one of the consequences they must accept is that they may get shot.
If this happens, they don't really have the right to complain.
Whether the response of the victim is legal, or morally justifiable, is irrelevant. Shot is shot. It is an undeniable possible consequence.
Perhaps, with the benefit of hindsight, the now deceased young burglar will make better choices in his next life.
Like not robbing people.
Life can sometimes appear harsh, but in the long run, it often proves to be fair.