I've been using ear plugs for live music both as listener and performer for ages. I consider them essential.

They can even improve listening quality. For years while going to concerts I thought that speakers have problems at venues due to always hearing high pitched noise, usually on guitars. It turns out it was basically sound of my ears screaming that it's to loud. Problem disapeares with ear plugs.

I sometimes take them off during the concert wanting to hear things louder and regret it in an instance :)