They break up my path,
They promote my calamity;
They have no helper.
This verse appears in the midst of a long response from Job, answering the final argument proffered by Job's three "friends," Bildad's short, six-verse diatribe in Job 25. In the intervening chapters Job has told off Bildad (what a miserable counsellor he was), averred that he has remained righteous, and become sentimental about his happy, prosperous past. Here in chapter 30, he is letting everyone know just how deeply his present circumstance was humiliating him.
The chapter begins with Job describing his tormentors, the youths who taunt him as he sits in the dust, scraping his painful boils with a potsherd. He paints a picture of a group of outcasts, young men of no reputation and no lineage--as he says in verse 1, "whose fathers I disdained to put with the dogs of my flock," meaning that he thought less of them than even dogs, which were considered to be the basest of creatures in that part of the world. These low-lifes are gaunt and feeble from living off the land, and they dwell in caves or whatever shelter they can find. The townspeople drive them off when they wander too close.
Yet, in his miserable state, Job has become even lower than they--to the point that the off-scourings of the earth belittle him! They do not consider him to have fallen to their level, not by a long shot! No, they stand aloof, as if they are his betters, and spit in his face (verse 10)!
In Job 30:13, the verse in question, Job is illustrating the method of their assault upon him by using the metaphor of attacking a stronghold. In the previous verse, he says that "they raise against me their ways of destruction." By this, he means that they are building their engines of war and throwing up their own earthworks to enable them to destroy his defenses, thus they are plotting and planning his ruin.
Verse 13 continues the comparison to a siege. "They break up my path" suggests that they have blocked or demolished every escape route he might have taken to avoid destruction. He has nowhere to run.
He next says, "They promote my calamity." The NASB renders this, "They profit from my destruction." The NET Bible translates this as, "They succeed in destroying me." Keil and Delitzsch say it is more like, "They minister to my overthrow." The idea seems to be that these social and economic outcasts, who have no skills and never do anything well, are actually succeeding in bringing him down.
Thus the next phrase becomes more explicable: "They have no helper." They may be otherwise helpless, but in this matter, they do not need anyone to aid them. They are doing quite well on their own, thank you very much! Another idea may be in this phrase also: that it generally means that they are worthless persons, and no one from general society would stoop to help them--but in this case, the helpless need no help!
And so, Job goes on to say, he is ruined. He has no defenses against them, so he must succumb to their assault. His honor is gone, as is his prosperity. He has nothing and is nothing. How miserable Job must have been!