I just hate this kind of thing.
First of all, is there any other profession that has to put up with this. Substitute "lawyer" or "plumber" or even "doctor" for "teacher" in this meme, and it just sounds dumb. "Nurse," maybe. (Hmm. What do nursing and teaching have in common as professions. Could it be that they're not commonly associated with testosterone?) We don't expect any professionals to consume themselves in order to do their jobs.
Second of all, notice the use of "it." For the simile to really tracks, "it" should be "she," but as soon as we put it that way, the ickiness of the analogy becomes more obvious. Really? Do parents say, "I expect my child's teacher to consume herself in order to educate my child?"
If we walk into our child's classroom in March and find a teacher who is exhausted, worn down, barely functioning, do we think, "Excellent. This is going just as it should." Do we expect a teacher to somehow become a new, fresh candle every fall and be a burned-out stub every May, or do we expect this self-immolation to occur over the length of the teacher's career? If so, is the expectation that the burned-out husk of a self-consumed teacher should just die promptly after retirement, having been fully self-consumed?
This is a close relative of the hero teacher myth