People are willing to lose a small but predictable amount of money to avoid occasionally and unpredictably losing a massive amount of money. The former is a loss they can plan for and absorb. The latter might kill their business.
Traders are often happy to take the other side of that trade because they can trade against many counterparties, collect a small premium from each one, and try to ensure their counterparties won’t all fail in a correlated way.
You may have liabilities or income that exist outside of financial markets e.g. if I have 500t of wheat due to be harvested I might want to hedge enough to guarantee I can pay my staff - ive locked in the price of wheat, I might make less money as a result but my risk is lower.