I've invested in notes, so I'd like to chime in. Yes, owning individual notes can be somewhat complicated and tricky for newbies, but there is ZERO mystery in how professionals like PPR make money at it. Banks sell pools of non-performing notes at a steep discount, and these guys exit either through the property (via short sale, foreclosure, or flip) or through the borrower (modify the loan), with many strategies involving these two.
I invested in PPR's note fund so I don't have to deal with things like foreclosures, contacting borrowers, modification paperwork, etc. Yeah, you have to be an "accredited investor", but for many mustachians, that status is do-able: $200k income individually ($300k joint), or a million in net worth. Don't get scared off from people telling you it's just for multi-millionaires.
in early 2017, I put part of my SDIRA in PPR's 10% note fund - they've paid like clockwork - ACH wire every first of the month. Since then, I've put more non-retirement $ into their recent fund offerings at 12%. Same deal. Always pay on time, always in full. The only bummer is that the non-retirement distributions are counted as ordinary income, and taxed accordingly.
I had some business near PPR's office in PA recently and dropped into their office to see if I could talk to their group. Dave Van Horn (owner) was able to break away and meet with me for over an hour answering every question I had (like "if you got hit by a bus tomorrow, do you have plans in place to keep things running?"). Walked away very impressed. Any investment is a risk, but at least this strategy make total sense to me, and is attached to real property - something that has value even if everything else goes to hell.