In the post match interviews, European Captain Padraig Harrington said the crowds were great, the people of Wisconsin were really nice.
Whoever complained that these crowds were bad, you must of never watched the Ryder Cup before, or especially from Europe. The golf crowds at those events are just like soccer crowds in Europe, they very rowdy. The US crowds were very respectful, almost too much at times. Here, see the 2018 Cup in Europe.
Ryder Cup Crowd 2018 - YouTube