Thank you for providing that context and explanation (post #3); it's really helpful. This is apparently a large law firm. The secretary is saying that (in the secretary's opinion), the person applying for the job just wants a bit of experience that would be valuable for going into business for himself (that is, opening his own private law practice); he has little interest in a career with this large firm and very likely wouldn't be staying very long. In the secretary's opinion, employment of this applicant would therefore be speculative (something of a gamble)—because if he's probably going to leave in a short time, it's not worthwhile for the firm to invest in training him, involving him in the firm's activities, etc.