Assume that you have access to someone who is "on the system". How do you convince that person to CONSISTENTLY WANT to get off the system. Everybody will, at some point in time, tell you that they don't really want to be in the system. In their mind, they know that it's wrong. However, they are not consistent about it. They forget about it as long as you leave them alone.
If you try the Socrates Q&A approach they just evade, become non-responsive or get mad at you. Is Ayn Rand's suggestion to just abandon them and let them die really the only way?
First, I don't consider accepting government benefits by itself to be "looting." If someone receives benefits after paying into the system, if they abide by the associated laws established through our democratic republic, while standing against the system, I wouldn't consider them to be a looter. They don't want it, they didn't ask for it, but they are forced to pay into it anyway, so accepting some benefits in exchange is perfectly reasonable and moral.
However, for a true looter, I think the key to getting them to stop is for them to realize that they are literally putting their life at risk in the long term. A government strong enough to steal from others to give to them is also strong enough to steal from them to give to others -- or to just terminate the program.
In addition, the things they are receiving, using or consuming had to be produced by someone. Who? Are they willing to risk their life that those people will always be willing and able to produce for them?
In the long run, history clearly shows that looting can't be sustained. Where will it leave them if the system collapses? If they think it can't or won't collapse, have them look at some photos of Detroit.