Answering both you and GP I belong to the “some people” group you described in your post. It’s not that I don’t understand the math, it’s just that I don’t have the mental capacity and time in my life to take advantage of this arbitrage.
To illustrate - I have an acquaintance who transfers money between credit cards to take advantage of points, and sign-up offers etc. Were I to engage in such activity myself - assuming I know anything about myself at all, it is that I will 100% forget some detail or date and end up getting charged all of the delayed interest making me worse off than if I didn’t engage in such a scheme at all.
So it’s like that. Rather than chasing some optimization in a half-ass manner, I’d rather just pay off the debt and pay less of my money to the bank.
There's no other thing to do, however, other than what you're already doing with your otherwise unused savings (hopefully index funds). Put your money in that instead of paying the mortgage early, and you'll end up with more money at the end of the mortgage. It's about the simplest optimization possible.
To illustrate - I have an acquaintance who transfers money between credit cards to take advantage of points, and sign-up offers etc. Were I to engage in such activity myself - assuming I know anything about myself at all, it is that I will 100% forget some detail or date and end up getting charged all of the delayed interest making me worse off than if I didn’t engage in such a scheme at all.
So it’s like that. Rather than chasing some optimization in a half-ass manner, I’d rather just pay off the debt and pay less of my money to the bank.