why not bitcoin can be worldwide coin
Because not all of the people in the world can afford such coin, and, they are not tech savvy, they are just contented on what they have, ...
Actually a portion of the bitcoin's users are not tech savvy so its not the end of the world for others who are not also. I don't know what you mean by contentment whether they are contented on the way they earned or the amount they earned though I would say a lot of user are contented the way they earned thru signature campaigns and trading but they still strive to be richer and richer.
Bitcoin is scaling and on August 1 SegWit will now be activated. From thereon, we will await what will be the response of the miners and the community whether there will be a split or others who disagree would have a change of heart and will see the light.