The time value of money is the idea that an amount of money in the present is more valuable and is worth more than the amount of money in the future. Two things you'd need to consider when making this type of deal is putting yourself at risk of not getting the money and putting your trust into the person who owns you the money. You would need to consider that putting yourself in that position is your decision, no one elses. Ask yourself, "Can I trust this person?" or, "What if I don't get as much money as they promised?"
I hope this helps!