The problem isn't diversity its the lack of enforcement of cultural rules, national laws, and not forcing new groups to assimulate into the greater whole.
This happens BECAUSE of diversity "enrichment".
Your politicians are diversified, your policemen are, your military...
it is also always a way to destroy nations. This happened many times before.
King solomon championed diversity... his destroying his nation.
Hawai championed diversity... imported a bunch of foreigners. Literally made rules that everyone is equal except for natives who are 2nd class citizens. now reduced to less than 15% of the pop and dwindling. As everyone else gangs up on them to suppress them.
A country is for a specific culture/people. Otherwise they are just fucking over their own descendants.