It’s a forever mortgage, meaning you never pay it back, even in a thousand years, if you keep on refinancing from interest only to interest only.
If you can earn a higher interest rate from investing your money elsewhere, then go for it. But be sure to save if you go interest only.
The problem is that home equity used to be hard to get to. We have now monetized home equity; and when when people have money it burns a hole in their pockets. They spend it on SUVs, boats, fancy clothes, etc…
Personally, I like the peace of mind of having my house paid off at retirement. Imagine what life would be like if had no housing expenses. You could be goofing-off, traveling and taking it easy. I guess you could do that on home-equity too… ’til it’s time to pay the piper.