I’ve always thought Financial Loans are Debt Traps for Credit Cards. Is that true?

My Brother in Law received a letter from Lion something Financial for about 15,000. With I think 7% or 8% interest rate.

They have 3 or 4 cards and about 9k debt with some higher interest rates around 28-30%. It's about $300 per month. They always make the payments and are paying it down but still he really wants to do accept this loan but I don't think it's a good idea. Isnt there always something in the fine print that comes back to bite you really hard?