Wouldn’t the investment property only sink if sold under purchase price? Or if it can’t be rented?
Pretty sure that the interest rate on a HELOC will float after a certain period of time. So, your monthly payment/cash flow will change as The Fed changes rates. So if you had used a Heloc to buy a high priced home in early 2022 based on super low interest rates, your monthly payment could have gone up several hundred dollars as interest rates have shot up. And usually, if interest rates are increasing, home values and rents are declining, unemployment climbs, etc which leaves you extra vulnerable and reduces the number of opportunities for a safe exit.
I'm already hearing stories about high paid tech workers that recently purchased homes at the top of the market, and can no longer afford them after getting let go. Having more than one property linked and funded in the same way in that scenario just increases your exposure and chance for hardship.