I still can't get how you are thinking that developing some project can cater to both needs. These are two different groups differing in terms of income, standard of living, health conditions, employment, social status and so on. Catering to the rich might get you bigger profit per sale but lesser in frequency and opposite in poor.
Again there will always be a target audience for each project. But it would be difficult to market to both groups.
I am not saying it's impossible but seems unrealistic to me.
I would guess that one company could create two different products that cater them both. Like rich people and poor people all use facebook (maybe you think Jeff Bezos doesn't, but millionaires wives still do) or instagram, we see poor people and rich people there. Or a company that owns a lot of cows, they could sell cheap milk, or they could build almond milk or whatever or organic and so forth bla bla, and sell two different products.
One clothing company could create a basic shirt, and sell it to everyone for cheap, whereas they could create expensive coats and sell it to rich. All in all, there are methods where EVERYONE could buy from you. Biggest example has always been social media. Look at twitter, Elon Musk, worlds richest person tweets probably more than the poorest person in the world, and both help twitter earn money from the ads.