Agreed except for your mischaracterization at the end. An I/O mortgage is a leveraged asset speculation you live in, without the “forced low interest savings” of traditional mortgages.
Historically, real estate has always appreciated at a health rate except during a handful of tail events. It’s less speculation and more allocating capital elsewhere versus dead capital in your home (and if the interest rate spread between the note and your other investment growth opportunities is significantly robust to make the effort worth while).