Walmart is able to undercut smaller and more specialist companies forcing them out of business. Since many believe small business to be the backbone of the economy - shopping at Walmart is a contribution towards a monopolistic economy with higher unemployment rates and lower minimum wage.
Also straining our government budget because Walmart treats its employees like poop, forcing them to use welfare. Also allowing Walmart to keep treating people like poop. And the environment. Also other bad stuff that I can’t remember because it is 2 am.