If you can't afford to lose it, you can't afford to lend it. Even if it was someone you knew well and not a relative stranger on the internet there's a fair chance you won't get repaid.
That doesn't mean you shouldn't help people financially when you feel compelled to do so, it just means you need to do so with the understanding that you might be out some/all of that money and you should also think through how that will impact your relationship with the person.
Collateral certainly decreases/eliminates the chances of you coming up short but it's also telling the person that you don't trust them much, and as you mentioned in this case is not an option.
Regarding your comment about a simple contract being sufficient, legally yes (most likely), and you can find free loan agreement templates online, but probably not worth the cost/effort to try to go to small claims court to collect, especially if they live in a different state. Proving a debt exists can be much easier than collecting on the debt.