They are studying for the intent that one day they will be teaching. It's like a student taking loans out for 12 years to pursue a PHD. Learning Torah IS a job, the same way research is. Unfortunately, in a secular state, learning Torah is NOT a job, even though it leads to teaching.
That's completely untrue on multiple counts. You are trying to find ways to justify the kollel system. Well, feel free to justify it to YOURSELF as you wish with whatever logic you choose, and feel free to give as much of your own money to that system as you want. But the discussion (the comment I replied to) centered on the halachic
obligation of the people at large to fund a kollel system of an entire society of people who refuse to work and choose to learn full time. Or an individual to give to one such person. From what I understand, there is no such obligation.
Most are not in kollel to become teachers or any profession. Even the ones who are, training for a profession is not the same thing as being in a profession!
And since when do I pay for phd candidates? The institutions themselves offer the stipends. They make their profits on other things. People in law school and medical school take out LOANS. People getting masters degrees (usually what teachers get) take loans or get partially funded by their employer. So your logic doesn't even make sense, but again, feel free to go w what you like for yourself, I'm talking about an entire society of people demanding payment and support from the rest of a country while refusing to work. Then you really have no place to say anyone is required to do this.
Even receiving money to teach torah is a machloketh. But most poskim allow it (unlike Rambam) for certain circumstances. Those circumstances do not include taking money to LEARN Torah while not teaching it, either now (all of them) or in the future (most of them).