"Why won't this dumb algo, designed by professional finance people tested on millions of data points, lend money to my home made amateur trading algo?"
FWIW I have borrowed money from family members, but to only bridge real estate transactions over short well defined time periods.
I've also had bad experiences of lending money to friends, and as the proverb goes losing both friends and money.
Personally, I think it's usually better to treat it as a gift. Then if they repay you it's a bonus.
(Not tax advice!)
It's very stressful trading with OPM. I doubt many people on this thread have enjoyed the pleasure of losing 1bn in a week. I can tell you it's not much fun.
When you actually know the people involved and will have to look them in the eye at Aunt Mauds funeral and explain how you lost a chunk of their inheritance on a speculative trading venture... it's much worse. Even though the sums involved are much smaller.
Agreeing to pay a 7% coupon every year irrespective of performance creates yet more stress, and makes it more likely you will do something stupid that will hasten your implosion.
Anyone who thinks any kind of trading profit is effectively guaranteed, is fooling themselves. I have been on ET for 7 years now. I have seen many such people come and go in that time. I doubt many of those who left did so because they had retired from trading with a vast fortune. Most likely they blew up.
I note from your profile you have also been here for a long time- since 2014 (I initially assumed from your post count that you were a relative newcomer). So clearly you are one if the lucky ones. But as others have said, you shouldn't extrapolate from that single data point to all possible futures. You are also assuming the OP has the same likelihood of success as you did, which again is a huge assumption.
Finslly saying someone is definitely a loser is very risky unless you are sure they are. Otherwise it just weakens the argument...
GAT