When they say that you should take the vax to protect those who are already vaxxed, it doesn't seem to make any logical sense at all. So you try reasoning with people who are parroting this. I would say no point you should look at it from "their angle". By them I mean those who are pushing the vax.
They know that if you get vaxxed your immunity will go down. So you protect those who are already vaxxed by taking the vax yourself so your immunity is also down. Its a classic communist tactic, promote equality so that you will not know what achievement through merit looks like. Also when you try to achieve they do the easiest thing to do, pull you down. When everyone is poor, it easy to govern, similarly when all sheep are sick, easy to make them submit to any medical tyranny you want. This way this makes perfect sense.