At what point should you lend someone money and how much I've also listened to @James altucher the 15 rules of not going broke
1. Don't lend money to family or friends
2. Don't lend money to people you care about
3. Lending is a transaction between two people who hate each other
4. If they are broke, don't lend them money
They will only be broke forever
5. The rule of 72 applied to lending money. If you are going to get 1% interest on your loan then the person has to pay back double so that you get 2%. So 72 divided by 1% gives you how many years it takes for you to double your money if you
Just use an online calculator if this doesn't make sense. For instance, if I lend $1 million at 1% interest, in 72 / 1 = 6 years I will have doubled my money.
But remember, there's always inflation and the value of your currency can change so this is just a rough guide.
Also, if someone defaults on a loan and they are not honest with their finances (like when applying for a loan), then it's probably better not to lend them any more than what they already owe you but that's up to you. Some people like to give second chances and some don't. It's up to the relationship with the person asking for the loan but remember...
You're not doing anyone a favor by giving them a loan they can't afford and which will ruin their lives (see rule #4). This is why I say, "don't ever lend anyone more than twice what they already owe you." And even then, think hard about it because odds are good that if they were in debt before ,they'll be in debt again .