As a note, on the site you frequently misuse the word “interests” instead of “interest” without S.
Thank you! Obvious mistake. To be honest, I'm not English native and I struggle to find balance between formal/informal for such kind of app/content :D "Installment" sounds so exotic for me :D
Of course, there's the matter of risk over time. We're very close to paying off the house we bought in 2009. For much of that period, regular bank interest was basically nothing, so it was clearly better to pay the mortgage than leave the money in the bank. A mortgage is a bond, so the 'return' on that is basically fixed and predictable. Other investments that might do better are less so. So there's a choice there. Over the same time, a broad index fund might do better, with acceptable risk, but again, there's no guarantee. We are, however, looking forward to being able to live more or less rent-free.
Yeah it's a matter of timing and security/stability game. To be honest, I didn't consider extra payment as an option for myself, but in current circumstances it really makes sense: not a risk-free investment alternative to 8% mortgage :) But when interest rates will go down, it can change. With a tool I just wanted to show numbers - for sure there is more to consider, but it should help to have a insight to bare numbers. Thanks for comment!