Why do people who vote no have to be apart of the union

Long story short my work became unionized last year and I said no, myself and very few others actually read the contract and nothing was different other than we are now promised certain things (which we always got anyways) and surprise surprise it's easier to lose our jobs now... I've seen many people lose their job and not a single one has gotten their job back.


So. Clearly I don't like the union is there any possible way to opt out of a useless union that just takes our money and does nothing else?