Social welfare as in funds for safety nets and public spending, like free healthcare, education, and improved disability, unemployment, and welfare benefits. US chose to spend trillions militarily that otherwise generally could've been allocated to those types of public spending within the US as well.

Refugees that Europe deals with is mostly Syrian and Afghani. The US supplied weapons and support to Syrian rebels and weapons to anti-communist mujahideen. Now, hindsight is 20/20, but Assad was literally using chemical weapons on Syrian citizens. The Taliban was wantonly wreaking destruction across Afghanistan causing the refugee displacement. These are complex issues when it comes to human rights abuses and geopolitics. My point is that the US paid a price in attempting to be world police, regardless of the outcome. It wasn't economically beneficial as the grandparent comment stated.