And that is why it is a personal choice. What risk level are they willing to live with to get the vaccine they prefer?
Your premise is that there aren't enough shots for all those willing to receive the vaccine, which means that shots are not sitting around waiting for arms and the total vaccinated will be the same, so if I delay someone else will be vaccinated in my place. Making it purely a personal decision not a public health one. The only thing waiting does is shift who remains personally vulnerable. A dose in my neighbor's arm provides just as much community protection as a dose in my arm.
While I ultimately didn't have to, I was personally willing to live with a risk of delay in getting the vaccine. I've got a very good history of both knowing what precautions are necessary, and being able to take those precautions. So for me, personally, a delay of up to a month would have presented an acceptable risk to get the Pfizer vaccine (which offers significantly better protection) rather than J&J. I probably wouldn't have delayed more than a week to get Pfizer over Moderna - but I hadn't made a firm decision.
I'm not in a position to judge anyone else's personal evaluation of which vaccine is appropriate for them, or why. My advocacy is purely that each person should always be making medical decisions for themself. Your decision to get whatever vaccine is available is perfectly fine, as was mine to specifically seek out Pfizer (and be willing to delay vaccine to get that specific vaccine), as is that of the OP to try to reschedule to get J&J. My choice - and the choice of the OP - may not be the choice you would make. But that happens all the time in medicine. There are options, and different people choose different options - and what someone else decides about their body is not necessarily what I would decide for my own.
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