I will say that during that time, the HELOC interest rates were very low.  

And, just maybe you’ve purchased at a point where Detroit has hit its low, bottomed out, and is set to reverse trend and grow.  

That’s why you get a discounted interest rate and a lower downpayment, because owne occupant properties are low risk. 

It is not low cost.. you need 7-8 rooms per house to make it decently profitable. 

You can have an increase in population and still have a low demand for rentals or a low enough demand that rental rates do not outpace T&I for awhile.

I have heard about low cost granite / stone, i just don't know where to get it. 

Not too bad when the inventory is low, the number of sales is low (like a 30 year low), interest rates are high and prices are high. 

With 20 properties, you’d build a nice, diversified income stream over time.Why Choose It: Low entry barrier, easier to pivot if a deal goes sideways, and you can scale at your own pace.Challenges: It’s time-intensive—sourcing 20 good deals takes hustle, and managing scattered properties (even with a system) can feel like herding cats.

They used lasers to find the low spots and used "push piers" to lift those areas. 

From our experience with clients, you’d typically expect to pay around $1,000–$1,500 for a single-property return, depending on your situation.If that $6K includes monthly bookkeeping and accounting, it could be reasonable; it could also be low, or high... it all really depends on the number of transactions, bank/credit card accounts, and the complexity of your finances.