There are three levels of integration: technical, social and cultural. At the basic level it is the technical integration. Traffic rules and office manners belong to this category. To some degree, you have to integrate at this level.
At the intermediate level it is the social integration. For example, you should hold the door for those who come after you. Another example is when you hand over a knife, you leave the handle for others. It is not mandatory for you to integrate at this level, but it is to your benefit if you do.
At the highest level it is the cultural integration. It seems that you would not benefit from this integration in terms of material gains. However, what you really get is the spirit freedom, enabling you fly from one spirit world to another one.
So why integrate? If you need to work and live in a new world, even as a labour, you have to integrate at the technical level; If you want to work as a so called professional, you have to integrate at both the technical and social levels; If you want to work toward the so called mainstream society, you have to integrate at all levels including the cultural level. Do not try to assume that you can buy the highest integration status because you have enough money.
Yes, birds of a feather flock together. The problem is if birds of different feathers have to live together, do you think that the newcomers should live the way the ealier birds have lived? I am afraid that there would be no options other than accepting it.