The biggest secret to keeping your wealth.

No matter how good the relationship is, never touch areas you're unfamiliar with, and never lend money you can't lend.
Unless there's one situation: you personally really like the project, are willing to study it deeply, understand the entire logic, and find it reliable—then you can give it a try.
If it's only because the relationship is good, don't put your money in.
No matter how good the relationship, it can't replace knowledge;
No matter how good the opportunity, it can't bypass risk control.
Also, I advise everyone not to casually bring up investment opportunities with friends, because once you do, your relationship changes. The way others evaluate your relationship will be reassessed.
When you do bring it up, think clearly: what are you asking them to invest in, why invest, and what the possible returns are. All of this must be presented to them. Even if you don't provide a written plan, at least have a simple description.
Generally, people who can make money are very smart and also hate baseless things. When they see a line like "I have a good project, are you interested in learning more?" with no other information, they feel their intelligence is being insulted.