I think the stats that really drove the point home for me, was when I heard that the people who were the most successful investors were the ones who died or forgot their account log-in.

Original Motley Fool article (it does appear looking for the study now that this might be an urban legend, as there is no evidence of the original study)

From an analysis of client portfolios between 2003 and 2013, Fidelity found that their best investors were those who never touched their shares. But these weren’t investors with nerves of steel or those that somehow managed to pick winning shares from the outset. Fidelity’s most successful investors were already dead.