There is a significant group of people who feel they are healthy and don’t need to worry about COVID. They talk about vitamins and exercise and their immune systems and that they never get sick and even when they do it last for a few days.
Another group of people are religious fanatics (not to be confused with people who are very religious and also very sane) and the fanatics are terrified of government control and believe every conspiracy theory about Bill Gates trying to kill or sterilize Black people and track everyone else to covid was a way to bring in socialism to the USA.
Sometimes those two groups overlap.
Not everyone who believes the conspiracy theories are religious zealots, some are just sucked into the fear mongering.
Then you have people who were wary regarding how fast the vaccine was developed. That is not totally irrational. No steps were skipped when developing the vaccine, but there is always a chance that when the vaccine is finally put on the market that new side effects will be discovered. Also, since it was developed quickly any long term side effects would be unknown, although there seems to be close to zero reason why something would change or develop over the long term. I would not have wanted the vaccine the first month it came to market. Let the first million go ahead of me then I felt fine putting my arm out. Some people needed 20 million people to get it along with some friends and family before they were ready.
Then you have people who just don’t trust the medical establishment.
Other people think they are calculating the odds right. If they get the shot they 100% got the shot. If they never get covid they don’t have to worry about effects from covid. If they get covid only a certain percentage get very sick, etc.
Quite a few people were/are very afraid of an anaphylactic reaction. The two people in my life with this fear finally got vaccinated. One just had her second shot on time the other is delaying her second shot. Both had to know medical care was close by to do it and I don’t mean a pharmacist with an epipen.