ruinously
🇺🇸
/ˈruːɪnəsli/
🇬🇧
/ˈruːɪnəsli/
in a way that causes financial disaster or extreme expense
The company went bankrupt after investing ruinously in a failed project.
in a way that causes severe harm or damage
His ruinously risky investment strategy led to the downfall of the company.