"have to": If I don't, they'll shoot me
"need to": It is a moral imperative for me to do this
"WILL": Because of course this is the case
"need to": It is a moral imperative for me to do this
"WILL": Because of course this is the case
When people say the government has a monopoly on violence, this is what they mean. Eventually, violence will be used to ensure compliance. Most people comply before that happens, under threat of it.