https://www.telegraph.co.uk/news/20...ng-juan-carlos-bows-public-life-mixed-legacy/
Telegraph writes that JC retired because Felipe did not invite him to Seville to attend Arms Day, an event he has not attended since he abdicated ... but no doubt his retirement has to do with his EGO!
Or perhaps he is an elderly man with poor health and isn't up to doing anything much other than taking things easy and enjoying whatever pleasures he can...