>>510346437 (OP)Money, influence, expansion, and colonization.
Diasporas are established in wealthy, corrupted countries where a colony provides low-income labor for the greedy upper classes. Colony sends money back, breeds, does not integrate, and bleeds an area dry. When too many opposing diasporas are parasitically feeding - violence ensues as expected.
If the host decides to take actions in reducing immigration, influence of the diasporas it's countered with hollow accusations to make the host feel bad, even through the foreigners are doing those accused actions already. And the multiculturalist cult members in the host country will sabotage any effort at healing.
The host country eventually dies by balkanization and regional war. Diasporas are likely abandoned by mother countries to fend for themselves as their monetary value ceased. Or supported if land acquisition is the goal.