This question reminds me of the Stephen King Novel 11/22/63. I'd worry about the impact that would have on others around me, and as well as my own ego. From others perspective it might get quite frustrating seeing someone win at absolutely everything. I'll probably get over confident with taking huge risks, which might cause tension with my loved ones. If I could do it only once though, it would be a day before a major lottery draw, win it, live it and if that doesn't work out - I'll have a save point to return to.