I've made low double-digits for 10+ years with pretty much hands-off private lending. I tried many algos (and understand them and system design/parameters well) and lost money. I kind of know what I'm talking about.LOL, now you go into real estates and lending space. These are just another bets, there is no sure double digit return guaranteed anywhere. I hope you understand the real estate market deeply and the other markets you mentioned. It seems you have no trust in whatsoever published results anywhere (on internet). He is looking for higher returns he already said, so having no risk is no fun as always. And you are just mentioning other lower correlations bet. You should not do that, it might only confuse SimpleMeLike with no further improvement for him.
It sounds like you don't understand hindsight bias and how backtested results never play out in real time. Ditto for strategies that work for a while in certain markets (like buying dips/selling puts in bull markets) and work well until they don't.