Most things cannot be forced on people or society. People need to reach their own conclusions. I do not tell people to be vegan. I show and explain to them what is happening to animals. It's not difficult to see that they are treated cruelly. When people realise that is the case, and that they have the power to stop some of that cruelty, we hope that they take the next step and do so.
Many people make the change, but sadly also many do not stick to it. Overall, the number of vegans and vegetarians are increasing, but so are the number of animals being killed. Progress is slow, but the world would not be able to handle rapid progress anyway.