It's a belief, yes. It's not a blind belief, because there's some data on the risks of the vaccine and on the risks of COVID-19, and on the decrease in risks of COVID-19 to those vaccinated, but it's still a belief and a gamble.
I understand it only partially. For me it is sad that we aren't able to prevent contagion by collective prevention (government mandated maybe, but ideally voluntary)
and then have to grasp on those hopes that a vaccine will quickly bring us to where we were before, not realising that wasn't such a beautiful place to be if it led here.
I mean complete lockdowns are hard on people, but short complete lockdowns combined with voluntary less travel, more social distancing, masks, washing and so on should be quite effective and bearable. EDIT: I mean if everyone abides, which doesn't happen]
It's kind of sad that if we suddenly stop doing banal things the economy collapses. Confirms that we have a shitty economy, unberable imbalances, lots of expense in wasteful areas and underfunded health systems and education. And lots of people loving it.
Still the reality being sad is no reason to deny reality, not even reason to change it when so few agree, so I can understand the urge to vaccine before at least 2 year trials. Kind of. Not much.