As an ecology major: maybe don't try comparing human society to ecology. Ecology is a really fucked up system if you really think about it with organisms constantly trying to eat or starve each other and dying as horribly and with as much suffering as they lived. Is that what we want in our society of intelligent, logical creatures? Plenty of other animals gave figured this out and formed cooperative social groups where individuals do things with the explicit intent to benefit the collective, why can't humans?
Consult Maslow's Pyramid. If you can't afford to feed yourself or your family, don't have stable housing, clean water, or social mobility, chances are "but you're so diverse!" isn't a consolation in your eyes.
Finally, the issue with rich (human) places being less diverse is entirely the fault of capitalism favouring the richest, and colonialism destroying the existing cultures. It's absolutely not caused by simply having more resources. Which, what the hell are they going on about rich places (their implication being the US and Canada) having existed for not that long? No no, it existed for ages, but y'all killed all the indigenous people and installed a fake culture on it and are pretending that it was the first one. Also, what about Western Europe? It's existed for ages too, yet is about as (un)diverse as the US or Canada with each country basically being its own ethnostate. In fact, the US and Canada are more diverse than most Western European countries due to having more immigrants.