Wealth is stuff that people want. You create wealth by creating stuff that other people want. http://www.paulgraham.com/wealth.html has a long version of this explanation.

The last 200 years have seen a dramatic transformation as we have found ways to efficiently create more wealth, with the result that we all have more stuff that we want than pretty much anyone used to. Both new kinds of stuff (effective medicine, gadgets like washing machines, electronic devices...) and the kinds of stuff we used to have (food, potable water, etc...).

And yet, people still emotionally fall prey to the old fallacy that more for thee means less for me. The truth is that there is no society on record that has managed to lower inequity without major disaster such as war or plague. And also no society on record that has managed to increase the prosperity of the poor without seeing income gaps rise.

(Read Enlightenment Now for a lot more detail on both of these phenomena.)

Or, as Margaret Thatcher put it, "...he would rather that the poor were poorer provided the rich were less rich." (See https://speakola.com/political/margaret-thatcher-on-socialis... for the full quote.)