Why did the nearer kinsman refuse to redeem Elimelech's land?

Answer: It would endanger his own estate

When told he must also acquire Ruth, he said, "I cannot redeem it myself, or I would jeopardize my own inheritance."

“The kinsman-redeemer replied, “I cannot redeem it myself, or I would jeopardize my own inheritance. Take my right of redemption, because I cannot redeem it.””— Ruth 4:6 (BSB)