In theory, there are couple benefits:

* Cheaper products for everyone

* Competition drives innovation

* Lower risk of large-scale wars

* Ship high-pollution industries overseas

* Improved price stability

In practice, it falls apart because...

- US has a poor social safety net. Low-income workers often end up jobless or in even lower skilled jobs

- Globalism builds bigger corporations, which actively suppress competition

- Big direct wars are replaced with constantly simmering proxy wars

- We can't control environmental degradation in other countries