When your justification is an uncertain investment, it isn't that hard of a concept to realize you're wrong. You're literally the only person I've ever seen advocating for the lump sum payment as the financialyl sound move when it quite nearly halves 100% sure income.

Inflation is also much less of a concern when you're talking about literal millions of dollars, unless you're talking about the Zimbabwe national lotto. If you're living in a way that your ability to live with $15,000,000/year towards the end of a 30-year annuity payout has materially changed, you have bigger issues than inflation going on.