People seek to change the minds of others because their opinions (and subsequent actions) often affect the people themselves.
A simple example of this would be abortion.
A simple example of this would be abortion.
Regardless of your stance on this, how others think and vote will affect other people.
For example, I am pro-choice. I believe people should have a right to access abortion if necessary. I don’t need to change someone’s mind if they don’t personally want to support abortion, but I do need to change their mind if they want to vote for people who will restrict that right.
See also: climate change.
There are many areas where you can and should agree to disagree and there will always be middle ground compromises in the details, but some issues really are black and white. Either you believe other people should have access to abortion or you don’t.
Also, and I hope this is obvious, the point is not whether you think abortion is right or wrong, it’s that other people’s decisions can affect you or your family or the world in general.
Even if we assume that "it's a personal choice" is some kind of natural/god-given/obvious default (which historically it hasn't been), we'd still to work to change the minds of people who think otherwise...
For example, I know many Icelanders are quite proud of how they have 'solved' the problem of Down Syndrome in their country by good prenatal testing. I strongly suspect women in countries like this face tremendous pro-abortion pressure when they consider carrying these children to term and welcoming them into their families.