$100m poster here.
You duck-brained twig. No, you wouldn't be better off taking $4m in your scenario unless you're damn old already. You have no idea about the power of compounded interest (would be a huge help in real life, not available in your scenario) and compounded inflation (will kick your ass in your scenario).
Those two things plus risk aversion and a desire for a healthy dose of cash led to my $100M figure.
For example, my $100m was based on spending $200k a year in today's dollars. A lot of money, sure. But not ultra rich cash. I want that because I will give up work, which sucks for a lot of people, and want to have something to make up for that. Plus I'll have lots of free time to fill. And I wanted to be conservative. I want access to good healthcare and that ain't getting cheaper. Plus your "spend only" rules create risk and I want to be compensated for assuming that risk.
Then I used 5% inflation. Higher than we've seen. But totally possible. We are printing money like there's no tomorrow. We are not immune to money woes hitting other countries like Greece. Plus, even with that high number, a brief period of hyper inflation and I'm wiped out anyway, and hopelessly destitute under your no work rule. Hyper inflation seems hard to comprehend happening in this country but a lot can change given a long time frame.
The uncertainty of things happening in a long time frame is a risk I'm assuming under your never work again rule. If I can't bounce back by working after some shit hits the fan, I better get some extra cash for taking on that risk.
Speaking of long time frame, I chose living for another 68 years. I could survive to be over 100.