Is it not an issue if your group becomes less powerful than other groups? You are then putting yourself at their mercy, and we cannot assume that everyone has the same values (they don't).
Sure of course, I was too vague. I’m not referring to our descendants having different values from us or myself. We do have some control over that, but not complete control, and exerting whatever control is available in the modern day risks future blowback. We are in agreement here.
I’m referring to the value of not persecuting based on ethnic or cultural background.
Not everyone in the world holds this value, and relocating to different land is not what makes a person hold one value or another.
So if groups who don’t hold this value grow numerically to the point where the lack of this value becomes dominant, we are putting our own group at risk of being subjected to it in the future, which seems rather unwise.
You shouldn't be OK with them having any random values, either.
If you have a civilization, you have a vision about life, and what's good and what's bad, and you want to see it to continue.
That some of them will inevitable change over time is not the same as you preactively having no preference and guidance for your offspring whatsoever, and thinking "no problem, anything goes".
> If you have a civilization, you have a vision about life,
Do you?
Your 'civilization' doesn't run on some kind of command economy five-year-cultural plan. Its values and views of what's good and bad are just some (often dystopian) local maximum it's stuck in.
Not to mention the obvious - what if you strongly disagree with your civilization's values?
A group having more power has little to do with numbers. If that was the case the rich would be more numerous than the poor, and India would be the most powerful country in the world.
The "power" of a country, however you define it, lags the population growth. China was the biggest country for decades, its power only really started exploding some 10 or 15 years ago.
That's an incredibly short sighted way of looking at countries. The US was never the country with highest population growth, and right now is also heading into a demographic collapse.