You have not figured out how DAI works. Read the documentation. To receive 100 DAI, you need to block other coins or tokens in a smart contract for $ 150 at the current exchange rate. When your collateral is worth $ 100, Maker will sell your collateral and burn the DAI received.
As long as the coins we have are stable, they are made by companies that have good fundamentals and are trusted, I don't think we need to worry.
DeFe's system is very complex, and those who have not figured out how it works at the very beginning will always see the pitfalls.
Maker DAO has passed many audits from well-known companies and has not yet been hacked.
If someone is interested, then upon request in Google, you can get all the detailed information