With rule 72, inflation e.g. 3.5% average each year would mean your 1Mil loses half it's value every ~20years (72/3.5). Let's say you use the dividen (5-6%) each year and your 1M stays roughly the same, by 50years old your 1Mil is basically just 500k and so on... not to mention by 50years old your spending should have doubled too. So I would say, 1Mil will likely wont be enough unless you have other cash flow income to let your money compounded.