Your friend will have a difficult time with rentals because he's not screening the applicants or enforcing the lease well enough. 

That was one of the most difficult and time consuming things when I was managing my own properties.

Detroit would be a difficult market to utilize a DSCR loan in due to the low amount of monthly rental income coming in. 

Both of those towns have stringent rules about STR's that can make it more difficult to find the right property that will fit your strategy.

With the new NAR ruling it's making things even more difficult.  

Hi Haoyang,It's pretty difficult to find, but just with the resources available to me I was able to spot a few fourplex listings that were somewhere around $1.25M.

it is very difficult - much more difficult than advertised, and more difficult now than it was a few years ago because of the increase in interest rates and the heightened competition for distressed deals.the issue is this: you're up against other investors and businesses spending tens and sometimes even hundreds of thousands of dollars a month on marketing. 

Welcome to the BP community and best of luck in your Investing career!

It is difficult doing this from a distance. 

I’m in a traditional career now and would love to scale up investing in some real estate over the next several years.