If bullet number 4 is correct, it sounds like a good idea. I would have to see proof that bullets 2 and 4 are correct in order for me to agree though.
3) is far fetched and would be catastrophic regardless, and 1) may not be viable because the 15 days of the month where the far side of the moon is facing the sun, it isn't facing the earth. If placed on the other side, 50% of the month, earth would be blocking out the sun on the moon's surface, and the other 50% of the month, the near side of the moon wouldn't be facing the sun.
2) Manufacturing medicines, alloys, and materials that can only be produced in micro-gravity.
3) Protecting humanity against social breakdown and/or extinction in case of massive asteroid strike / global pandemic / etc.
4) Because every dollar that has been spent on space development in the US has put $7 back into the economy by way of spinoffs, technical advances, etc.